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1. Constraining the nature of the PDS 70 protoplanets with VLTI/GRAVITY

Author: Wang, JJ, Vigan, A, Lacour, S, Nowak, M, Stolker, T, De Rosa, RJ, Ginzburg, S, Gao, P, Abuter, R, Amorim, A, Asensio-Torres, R, Bauböck, M, Benisty, M, Berger, JP, Beust, H, Beuzit, JL, Blunt, S, Boccaletti, A, Bohn, A, Bonnefoy, M, Bonnet, H, Brandner, W, Cantalloube, F, Caselli, P, Charnay, B, Chauvin, G, Choquet, E, Christiaens, V, Clénet, Y, Coudé Du Foresto, V, Cridland, A, De Zeeuw, PT, Dembet, R, Dexter, J, Drescher, A, Duvert, G, Eckart, A, Eisenhauer, F, Facchini, S, Gao, F, Garcia, P, Garcia Lopez, R, Gardner, T, Gendron, E, Genzel, R, Gillessen, S, Girard, J, Haubois, X, Heißel, G, Henning, T, Hinkley, S, Hippler, S, Horrobin, M, Houllé, M, Hubert, Z, Jiménez-Rosales, A, Jocou, L, Kammerer, J, Keppler, M, Kervella, P, Meyer, M, Kreidberg, L, Lagrange, AM, Lapeyrère, V, Le Bouquin, JB, Léna, P, Lutz, D, Maire, AL, Ménard, F, Mérand, A, Mollière, P, Monnier, JD, Mouillet, D, Müller, A, Nasedkin, E, Ott, T, Otten, GPPL, Paladini, C, Paumard, T, Perraut, K, Perrin, G, Pfuhl, O, Pueyo, L, Rameau, J, Rodet, L, Rodríguez-Coira, G, Rousset, G, Scheithauer, S, Shangguan, J, Shimizu, T, Stadler, J, Straub, O, Straubmeier, C, Sturm, E, Tacconi, LJ, Van Dishoeck, EF, Vincent, F, Von Fellenberg, SD, Ward-Duong, K, Widmann, F, Wang, JJ [0000-0003-0774-6502], Vigan, A [0000-0002-5902-7828], Lacour, S [0000-0002-6948-0263], Stolker, T [0000-0002-5823-3072], De Rosa, RJ [0000-0002-4918-0247], Gao, P [0000-0002-8518-9601], Asensio-Torres, R [0000-0003-2990-0726], Benisty, M [0000-0002-7695-7605], Beuzit, JL [0000-0002-7391-479X], Blunt, S [0000-0002-3199-2888], Bohn, A [0000-0003-1401-9952], Bonnefoy, M [0000-0001-5579-5339], Brandner, W [0000-0003-1939-6351], Caselli, P [0000-0003-1481-7911], Charnay, B [0000-0003-0977-6545], Choquet, E [0000-0002-9173-0740], Christiaens, V [0000-0002-0101-8814], Clénet, Y [0000-0002-8382-2020], De Zeeuw, PT [0000-0003-4175-3474], Dexter, J [0000-0003-3903-0373], Eckart, A [0000-0001-6049-3132], Facchini, S [0000-0003-4689-2684], Gao, F [0000-0002-2581-9114], Garcia Lopez, R [0000-0002-2144-0991], Gardner, T [0000-0002-3003-3183], Genzel, R [0000-0002-2767-9653], Gillessen, S [0000-0002-5708-0481], Girard, J [0000-0001-8627-0404], Henning, T [0000-0002-1493-300X], Hinkley, S [0000-0001-8074-2562], Hippler, S [0000-0002-3912-6108], Horrobin, M [0000-0001-5451-7847], Kervella, P [0000-0003-0626-1749], Meyer, M [0000-0003-1227-3084], Kreidberg, L [0000-0003-0514-1147], Le Bouquin, JB [0000-0002-0493-4674], Lutz, D [0000-0003-0291-9582], Maire, AL [0000-0002-2591-4138], Mérand, A [0000-0002-1637-7393], Monnier, JD [0000-0002-3380-3307], Ott, T [0000-0003-1572-0396], Paumard, T [0000-0003-0655-0452], Perrin, G [0000-0003-0680-0167], Rameau, J [0000-0003-0029-0258], Rodríguez-Coira, G [0000-0002-4177-6433], Shangguan, J [0000-0002-4569-9009], Shimizu, T [0000-0002-2125-4670], Straub, O [0000-0001-5755-0677], Straubmeier, C [0000-0002-0671-9302], Sturm, E [0000-0002-0018-3666], Tacconi, LJ [0000-0002-1485-9401], Van Dishoeck, EF [0000-0001-7591-1907], Vincent, F [0000-0002-3855-0708], Von Fellenberg, SD [0000-0002-9156-2249], Ward-Duong, K [0000-0002-4479-8291], and Apollo - University of Cambridge Repository
Subjects: Orbit determination, Exoplanet formation, Long baseline interferometry, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics, Exoplanet atmospheres
Abstract: We present K-band interferometric observations of the PDS 70 protoplanets along with their host star using VLTI/GRAVITY. We obtained K-band spectra and 100 $\mu$as precision astrometry of both PDS 70 b and c in two epochs, as well as spatially resolving the hot inner disk around the star. Rejecting unstable orbits, we found a nonzero eccentricity for PDS 70 b of $0.17 \pm 0.06$, a near-circular orbit for PDS 70 c, and an orbital configuration that is consistent with the planets migrating into a 2:1 mean motion resonance. Enforcing dynamical stability, we obtained a 95% upper limit on the mass of PDS 70 b of 10 $M_\textrm{Jup}$, while the mass of PDS 70 c was unconstrained. The GRAVITY K-band spectra rules out pure blackbody models for the photospheres of both planets. Instead, the models with the most support from the data are planetary atmospheres that are dusty, but the nature of the dust is unclear. Any circumplanetary dust around these planets is not well constrained by the planets' 1-5 $\mu$m spectral energy distributions (SEDs) and requires longer wavelength data to probe with SED analysis. However with VLTI/GRAVITY, we made the first observations of a circumplanetary environment with sub-au spatial resolution, placing an upper limit of 0.3~au on the size of a bright disk around PDS 70 b.
Published: 2022
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2. First light for GRAVITY Wide

Author: Abuter, R., Allouche, F., Amorim, A., Bailet, C., Bauböck, M., Berger, J.-P., Berio, P., Bigioli, A., Boebion, O., Bolzer, M.L., Bonnet, H., Bourdarot, G., Bourget, P., Brandner, W., Clénet, Y., Courtney-Barrer, B., Dallilar, Y., Davies, R., Defrère, D., Delboulbé, A., Delplancke, F., Dembet, R., Zeeuw, P.T. de, Drescher, A., Eckart, A., Édouard, C., Eisenhauer, F., Fabricius, M., Feuchtgruber, H., Finger, G., Förster Schreiber, N.M., Garcia, E., Garcia, P., Gao, F., Gendron, E., Genzel, R., Gil, J.P., Gillessen, S., Gomes, T., Gonté, F., Gouvret, C., Guajardo, P., Guieu, S., Hartl, M., Haubois, X., Haußmann, F., Heißel, G., Henning, T., Hippler, S., Hönig, S., Horrobin, M., Hubin, N., Jacqmart, E., Jochum, L., Jocou, L., Kaufer, A., Kervella, P., Korhonen, H., Kreidberg, L., Lacour, S., Lagarde, S., Lai, O., Lapeyrère, V., Laugier, R., Le Bouquin, J.-B., Leftley, J., Léna, P., Lutz, D., Mang, F., Marcotto, A., Maurel, D., Mérand, A., Millour, F., More, N., Nowacki, H., Nowak, M., Oberti, S., Ott, T., Pallanca, L., Pasquini, L., Paumard, T., Perraut, K., Perrin, G., Petrov, R., Pfuhl, O., Pourré, N., Rabien, S., Rau, C., Robbe-Dubois, S., Rochat, S., Salman, M., Schöller, M., Schubert, J., Schuhler, N., Shangguan, J., Shimizu, T., Scheithauer, S., Sevin, A., Soulez, F., Spang, A., Stadler, E., Stadler, J., Straubmeier, C., Sturm, E., Tacconi, L.J., Tristram, K.R.W., Vincent, F., von Fellenberg, S., Uysal, S., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., Young, A., and Zins, G.
Subjects: Instrumentation - high angular resolution, Astrophysics - instrumentation and methods for astrophysics, interferometers [instrumentation], FOS: Physical sciences, GAIA, Astrophysics::Cosmology and Extragalactic Astrophysics, Astronomy & Astrophysics, Stars: individual - Orion Trapezium Cluster, Instrumentation - interferometers, HISTORY, ORION TRAPEZIUM STARS, Astrophysics::Solar and Stellar Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics, Science & Technology, supermassive black holes [quasars], Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, individual: Orion Trapezium Cluster [stars], ORBIT, ANGLE, LONG, Quasars - supermassive black holes, Space and Planetary Science, ANISOPLANATISM, Physical Sciences, Astrophysics::Earth and Planetary Astrophysics, high angular resolution [instrumentation]
Abstract: GRAVITY+ is the upgrade of GRAVITY and the Very Large Telescope Interferometer (VLTI) with wide-separation fringe tracking, new adaptive optics, and laser guide stars on all four 8~m Unit Telescopes (UTs), for ever fainter, all-sky, high contrast, milliarcsecond interferometry. Here we present the design and first results of the first phase of GRAVITY+, called GRAVITY Wide. GRAVITY Wide combines the dual-beam capabilities of the VLTI and the GRAVITY instrument to increase the maximum separation between the science target and the reference star from 2 arcseconds with the 8 m UTs up to several 10 arcseconds, limited only by the Earth's turbulent atmosphere. This increases the sky-coverage of GRAVITY by two orders of magnitude, opening up milliarcsecond resolution observations of faint objects, and in particular the extragalactic sky. The first observations in 2019 - 2022 include first infrared interferometry of two redshift $z\sim2$ quasars, interferometric imaging on the binary system HD 105913A, and repeated observations of multiple star systems in the Orion Trapezium Cluster. We find the coherence loss between the science object and fringe-tracking reference star well described by the turbulence of the Earth's atmosphere. We confirm that the larger apertures of the UTs result in higher visibilities for a given separation due to larger overlap of the projected pupils on sky and give predictions for visibility loss as a function of separation to be used for future planning., Comment: 15 pages, 12 figures, 5 tables. Accepted by A&A
Published: 2022
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3. Constraining the Nature of the PDS 70 Protoplanets with VLTI/GRAVITY ∗ ∗ Based on observations collected at the European Southern Observatory under ESO programmes 0101.C-0281(B), 1103.B-0626(A), 2103.C-5018(A), and 1104.C-0651(A)

Author: Wang, J. J., Vigan, A., Lacour, S., Nowak, M., Stolker, T., De Rosa, R. J., Ginzburg, S., Gao, P., Abuter, R., Amorim, A., Asensio-Torres, R., Bauböck, M., Benisty, M., Berger, J. P., Beust, H., Beuzit, J.-L., Blunt, S., Boccaletti, A., Bohn, A., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V., Clénet, Y., Du Foresto, V. Coudé, Cridland, A., Zeeuw, P. T. De, Dembet, R., Dexter, J., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Facchini, S., Gao, F., Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J., Haubois, X., Heißel, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houllé, M., Hubert, Z., Jiménez-Rosales, A., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Meyer, M., Kreidberg, L., Lagrange, A.-M., Lapeyrère, V., Bouquin, J.-B. Le, Léna, P., Lutz, D., Maire, A.-L., Ménard, F., Mérand, A., Mollière, P., Monnier, J. D., Mouillet, D., Müller, A., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Pueyo, L., Rameau, J., Rodet, L., Rodríguez-Coira, G., Rousset, G., Scheithauer, S., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., Dishoeck, E. F. Van, Vincent, F., Fellenberg, S. D. Von, Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Collaboration, The GRAVITY, Wang, J. J. [0000-0003-0774-6502], Vigan, A. [0000-0002-5902-7828], Lacour, S. [0000-0002-6948-0263], Stolker, T. [0000-0002-5823-3072], De Rosa, R. J. [0000-0002-4918-0247], Gao, P. [0000-0002-8518-9601], Asensio-Torres, R. [0000-0003-2990-0726], Benisty, M. [0000-0002-7695-7605], Beuzit, J.-L. [0000-0002-7391-479X], Blunt, S. [0000-0002-3199-2888], Bohn, A. [0000-0003-1401-9952], Bonnefoy, M. [0000-0001-5579-5339], Brandner, W. [0000-0003-1939-6351], Caselli, P. [0000-0003-1481-7911], Charnay, B. [0000-0003-0977-6545], Choquet, E. [0000-0002-9173-0740], Christiaens, V. [0000-0002-0101-8814], Clénet, Y. [0000-0002-8382-2020], Zeeuw, P. T. de [0000-0003-4175-3474], Dexter, J. [0000-0003-3903-0373], Eckart, A. [0000-0001-6049-3132], Facchini, S. [0000-0003-4689-2684], Gao, F. [0000-0002-2581-9114], Lopez, R. Garcia [0000-0002-2144-0991], Gardner, T. [0000-0002-3003-3183], Genzel, R. [0000-0002-2767-9653], Gillessen, S. [0000-0002-5708-0481], Girard, J. [0000-0001-8627-0404], Henning, T. [0000-0002-1493-300X], Hinkley, S. [0000-0001-8074-2562], Hippler, S. [0000-0002-3912-6108], Horrobin, M. [0000-0001-5451-7847], Kervella, P. [0000-0003-0626-1749], Meyer, M. [0000-0003-1227-3084], Kreidberg, L. [0000-0003-0514-1147], Bouquin, J.-B. Le [0000-0002-0493-4674], Lutz, D. [0000-0003-0291-9582], Maire, A.-L. [0000-0002-2591-4138], Ménard, F. [0000-0002-1637-7393], Monnier, J. D. [0000-0002-3380-3307], Ott, T. [0000-0003-1572-0396], Paumard, T. [0000-0003-0655-0452], Perrin, G. [0000-0003-0680-0167], Rameau, J. [0000-0003-0029-0258], Rodríguez-Coira, G. [0000-0002-4177-6433], Shangguan, J. [0000-0002-4569-9009], Shimizu, T. [0000-0002-2125-4670], Straub, O. [0000-0001-5755-0677], Straubmeier, C. [0000-0002-0671-9302], Sturm, E. [0000-0002-0018-3666], Tacconi, L. J. [0000-0002-1485-9401], Dishoeck, E. F. van [0000-0001-7591-1907], Vincent, F. [0000-0002-3855-0708], Fellenberg, S. D. von [0000-0002-9156-2249], Ward-Duong, K. [0000-0002-4479-8291], Woillez, J. [0000-0002-2958-4738], and Apollo - University of Cambridge Repository
Subjects: The Solar System, Exoplanets, and Astrobiology, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics
Abstract: We present K-band interferometric observations of the PDS 70 protoplanets along with their host star using VLTI/GRAVITY. We obtained K-band spectra and 100 μas precision astrometry of both PDS 70 b and c in two epochs, as well as spatially resolving the hot inner disk around the star. Rejecting unstable orbits, we found a nonzero eccentricity for PDS 70 b of 0.17 ± 0.06, a near-circular orbit for PDS 70 c, and an orbital configuration that is consistent with the planets migrating into a 2:1 mean motion resonance. Enforcing dynamical stability, we obtained a 95% upper limit on the mass of PDS 70 b of 10 M Jup, while the mass of PDS 70 c was unconstrained. The GRAVITY K-band spectra rules out pure blackbody models for the photospheres of both planets. Instead, the models with the most support from the data are planetary atmospheres that are dusty, but the nature of the dust is unclear. Any circumplanetary dust around these planets is not well constrained by the planets’ 1–5 μm spectral energy distributions (SEDs) and requires longer wavelength data to probe with SED analysis. However with VLTI/GRAVITY, we made the first observations of a circumplanetary environment with sub-astronomical-unit spatial resolution, placing an upper limit of 0.3 au on the size of a bright disk around PDS 70 b.
Published: 2021
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4. The mass distribution in the Galactic Centre from interferometric astrometry of multiple stellar orbits

Author: GRAVITY Collaboration, Abuter, R., Aimar, N., Amorim, A., Ball, J., Baub��ck, M., Berger, J. P., Bonnet, H., Bourdarot, G., Brandner, W., Cardoso, V., Cl��net, Y., Dallilar, Y., Davies, R., de Zeeuw, P. T., Dexter, J., Drescher, A., Eisenhauer, F., Schreiber, N. M. F��rster, Foschi, A., Garcia, P., Gao, F., Gendron, E., Genzel, R., Gillessen, S., Habibi, M., Haubois, X., Hei��el, G., Henning, T., Hippler, S., Horrobin, M., Jochum, L., Jocou, L., Kaufer, A., Kervella, P., Lacour, S., Lapeyr��re, V., Bouquin, J. -B. Le, L��na, P., Lutz, D., Ott, T., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Rabien, S., Shangguan, J., Shimizu, T., Scheithauer, S., Stadler, J., Stephens, A. W., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., Tristram, K. R. W., Vincent, F., von Fellenberg, S., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., Young, A., and Zins, G.
Subjects: Astrophysics of Galaxies (astro-ph.GA), Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics::Solar and Stellar Astrophysics, General Relativity and Quantum Cosmology (gr-qc), Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics - Astrophysics of Galaxies, Astrophysics::Galaxy Astrophysics, General Relativity and Quantum Cosmology
Abstract: The stars orbiting the compact radio source Sgr A* in the Galactic Centre are precision probes of the gravitational field around the closest massive black hole. In addition to adaptive optics assisted astrometry (with NACO / VLT) and spectroscopy (with SINFONI / VLT, NIRC2 / Keck and GNIRS / Gemini) over three decades, since 2016/2017 we have obtained 30-100 mu-as astrometry with the four-telescope interferometric beam combiner GRAVITY / VLTI reaching a sensitivity of mK = 20 when combining data from one night. We present the simultaneous detection of several stars within the diffraction limit of a single telescope, illustrating the power of interferometry. The new data for the stars S2, S29, S38 and S55 yield significant accelerations between March and July 2021, as these stars pass the pericenters of their orbits between 2018 and 2023. This allows for a high-precision determination of the gravitational potential around Sgr A*. Our data are in excellent agreement with general relativity orbits around a single central point mass, M = 4.30 x 10^6 M_sun with a precision of about +-0.25%. We improve the significance of our detection of the Schwarzschild precession in the S2 orbit to 7 sigma. Assuming plausible density profiles, an extended mass component inside S2's apocentre (= 0.23" or 2.4 x 10^4 R_S) must be 3000 M_sun (1 sigma), or 0.1% of M. Adding the enclosed mass determinations from 13 stars orbiting Sgr A* at larger radii, the innermost radius at which the excess mass beyond Sgr A* tentatively is seen is r = 2.5" >= 10x the apocentre of S2. This is in full harmony with the stellar mass distribution (including stellar-mass black holes) obtained from the spatially resolved luminosity function., published in A&A
Published: 2021

5. VI. Mapping the variable inner disk of HD 163296 at sub-au scales

Author: Sanchez-Bermudez, J., Caratti O Garatti, A., Garcia Lopez, R., Perraut, K., Labadie, L., Benisty, M., Brandner, W., Dougados, C., Garcia, P., Henning, Th., Klarmann, L., Amorim, A., Bauböck, M., Berger, J., Le Bouquin, J., Caselli, P., Clénet, Y., Coudé Du Foresto, V., de Zeeuw, P., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Filho, M., Gao, F., Gendron, E., Genzel, R., Gillessen, S., Grellmann, R., Heissel, G., Horrobin, M., Hubert, Z., Jiménez-Rosales, A., Jocou, L., Kervella, P., Lacour, S., Lapeyrère, V., Léna, P., Ott, T., Paumard, T., Perrin, G., Pineda, J., Rodríguez-Coira, G., Rousset, G., Segura-Cox, D., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Van Dishoeck, E., Vincent, F., Von fellenberg, S., Widmann, F., Woillez, J., Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)
Subjects: [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: International audience; Context. Protoplanetary disks drive some of the formation process (e.g., accretion, gas dissipation, formation of structures) of stars and planets. Understanding such physical processes is one of the most significant astrophysical questions. HD 163296 is an interesting young stellar object for which infrared and sub-millimeter observations have shown a prominent circumstellar disk with gaps plausibly created by forming planets. Aims. This study aims to characterize the morphology of the inner disk in HD 163296 with multi-epoch, near-infrared interferometric observations performed with GRAVITY at the Very Large Telescope Interferometer. Our goal is to depict the K -band ( λ 0 ~ 2.2 μm) structure of the inner rim with milliarcsecond (sub-au) angular resolution. Our data is complemented with archival Precision Integrated-Optics Near-infrared Imaging ExpeRiment ( H -band; λ 0 ~ 1.65 μm) data of the source. Methods. We performed a gradient descent parametric model fitting to recover the sub-au morphology of our source. Results. Our analysis shows the existence of an asymmetry in the disk surrounding the central star of HD 163296. We confirm variability of the disk structure in the inner ~2 mas (0.2 au). While variability of the inner disk structure in this source has been suggested by previous interferometric studies, this is the first time that it is confirmed in the H - and K -bands by using a complete analysis of the closure phases and squared visibilities over several epochs. Because of the separation from the star, position changes, and the persistence of this asymmetric structure on timescales of several years, we argue that it is probably a dusty feature (e.g., a vortex or dust clouds) made by a mixing of silicate and carbon dust and/or refractory grains, inhomogeneously distributed above the mid-plane of the disk.
Published: 2021
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6. Characterizing the morphology of the debris disk around the low-mass star GSC 07396-00759

Author: Lacour, S., Wang, J., Rodet, L., Nowak, M., Shangguan, J., Beust, H., Lagrange, A.-M., Abuter, R., Amorim, A., Asensio-Torres, R., Benisty, M., Berger, J.-P., Blunt, S., Boccaletti, A., Bohn, A., Bolzer, M.-L., Bonnefoy, M., BONNET, H., Bourdarot, G., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V., Clénet, Y., Coudé Du Foresto, V., Cridland, A., Dembet, R., Dexter, J., de Zeeuw, P., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Garcia Lopez, R., Gendron, E., Genzel, R., Gillessen, S., Girard, J., Haubois, X., Heißel, G., Henning, Th., Hinkley, S., Hippler, S., Horrobin, M., Houllé, M., Hubert, Z., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Kreidberg, L., Lapeyrère, V., Le Bouquin, J.-B., Léna, P., Lutz, D., Maire, A.-L., Mérand, A., Mollière, P., Monnier, J., Mouillet, D., Nasedkin, E., Ott, T., Otten, G., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Rickman, E., Pueyo, L., Rameau, J., Rousset, G., Rustamkulov, Z., Samland, M., Shimizu, T., Sing, D., Stadler, J., Stolker, T., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L., Van Dishoeck, E., Vigan, A., Vincent, F., Von fellenberg, S., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., Young, A., Adam, C., Olofsson, J., van Holstein, R., Bayo, A., Milli, J., Kral, Q., Ginski, C., Montesinos, M., Pawellek, N., Zurlo, A., Langlois, M., Delboulbé, A., Pavlov, A., Ramos, J., Weber, L., Wildi, F., Rigal, F., Sauvage, J.-F., Pawellek, Nicole [0000-0002-9385-9820], Apollo - University of Cambridge Repository, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Low Energy Astrophysics (API, FNWI), and Faculteit der Geesteswetenschappen
Subjects: 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Outflows, Context (language use), Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, circumstellar matter, techniques: photometric, 0103 physical sciences, Radiative transfer, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Earth and Planetary Astrophysics (astro-ph.EP), Physics, Debris disk, stars: winds, outflows, techniques: high angular resolution, Astronomy and Astrophysics, Radius, Stars: winds, Grain size, Stars, stars: individual: GSC 07396-00759, Astrophysics - Solar and Stellar Astrophysics, [SDU]Sciences of the Universe [physics], Space and Planetary Science, radiative transfer, Scattering theory, Astrophysics::Earth and Planetary Astrophysics, Low Mass, Astrophysics - Earth and Planetary Astrophysics
Abstract: Context. Debris disks have commonly been studied around intermediate-mass stars. Their intense radiation fields are believed to efficiently remove the small dust grains that are constantly replenished by collisions. For lower-mass stars, in particular M-stars, the dust removal mechanism needs to be further investigated given the much weaker radiation field produced by these objects. Aims. We present new polarimetric observations of the nearly edge-on disk around the pre-main sequence M-type star GSC 07396-00759, taken with VLT/SPHERE IRDIS, with the aim to better understand the morphology of the disk, its dust properties, and the star-disk interaction via the stellar mass-loss rate. Methods. We model our observations to characterize the location and properties of the dust grains using the Henyey-Greenstein approximation of the polarized phase function and evaluate the strength of the stellar winds. Results. We find that the observations are best described by an extended and highly inclined disk ($i\approx 84.3\,^{\circ}\pm0.3$) with a dust distribution centered at a radius $r_{0}\approx107\pm2$ au. The polarized phase function $S_{12}$ is best reproduced by an anisotropic scattering factor $g\approx0.6$ and small micron-sized dust grains with sizes $s>0.3\,\mathrm��$m. We furthermore discuss some of the caveats of the approach and a degeneracy between the grain size and the porosity. Conclusions. Even though the radius of the disk may be over-estimated, our results suggest that using a given scattering theory might not be sufficient to fully explain key aspects such as the shape of the phase function, or the dust grain size. With the caveats in mind, we find that the average mass-loss rate of GSC 07396-00759 can be up to 500 times stronger than that of the Sun, supporting the idea that stellar winds from low-mass stars can evacuate small dust grains from the disk., 22 pages, 17 figures, 4 tables
Published: 2021
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7. The SPHERE infrared survey for exoplanets (SHINE)

Author: Desidera, S., Chauvin, G., Bonavita, M., Messina, S., LeCoroller, H., Schmidt, T., Gratton, R., Lazzoni, C., Meyer, M., Schlieder, J., Cheetham, A., Hagelberg, J., Bonnefoy, M., Feldt, M., Lagrange, A.-M., Langlois, M., Vigan, A., Tan, T. G., Hambsch, F.-J., Millward, M., Alcalá, J., Benatti, S., Brandner, W., Carson, J., Covino, E., Delorme, P., D’Orazi, V., Janson, M., Rigliaco, E., Beuzit, J.-L., Biller, B., Boccaletti, A., Dominik, C., Cantalloube, F., Fontanive, C., Galicher, R., Henning, Th., Lagadec, E., Ligi, R., Maire, A.-L., Menard, F., Mesa, D., Müller, A., Samland, M., Schmid, H. M., Sissa, E., Turatto, M., Udry, S., Zurlo, A., Asensio-Torres, R., Kopytova, T., Rickman, E., Abe, L., Antichi, J., Baruffolo, A., Baudoz, P., Baudrand, J., Blanchard, P., Bazzon, A., Buey, T., Carbillet, M., Carle, M., Charton, J., Cascone, E., Claudi, R., Costille, A., Deboulbé, A., De Caprio, V., Dohlen, K., Fantinel, D., Feautrier, P., Fusco, T., Gigan, P., Giro, E., Gisler, D., Gluck, L., Hubin, N., Hugot, E., Jaquet, M., Kasper, M., Madec, F., Magnard, Y., Martinez, P., Maurel, D., Le Mignant, D., Möller-Nilsson, O., Llored, M., Moulin, T., Origné, A., Pavlov, A., Perret, D., Petit, C., Pragt, J., Puget, P., Rabou, P., Ramos, J., Rigal, F., Rochat, S., Roelfsema, R., Rousset, G., Roux, A., Salasnich, B., Sauvage, J.-F., Sevin, A., Soenke, C., Stadler, E., Suarez, M., Weber, L., Wildi, F., Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)
Subjects: [PHYS.ASTR.IM]Physics [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], [SDU]Sciences of the Universe [physics], 530 Physics, 520 Astronomy, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: International audience; Context. Large surveys with new-generation high-contrast imaging instruments are needed to derive the frequency and properties of exoplanet populations with separations from ~5 to 300 au. A careful assessment of the stellar properties is crucial for a proper understanding of when, where, and how frequently planets form, and how they evolve. The sensitivity of detection limits to stellar age makes this a key parameter for direct imaging surveys. Aims. We describe the SpHere INfrared survey for Exoplanets (SHINE), the largest direct imaging planet-search campaign initiated at the VLT in 2015 in the context of the SPHERE Guaranteed Time Observations of the SPHERE consortium. In this first paper we present the selection and the properties of the complete sample of stars surveyed with SHINE, focusing on the targets observed during the first phase of the survey (from February 2015 to February 2017). This early sample composed of 150 stars is used to perform a preliminary statistical analysis of the SHINE data, deferred to two companion papers presenting the survey performance, main discoveries, and the preliminary statistical constraints set by SHINE. Methods. Based on a large database collecting the stellar properties of all young nearby stars in the solar vicinity (including kinematics, membership to moving groups, isochrones, lithium abundance, rotation, and activity), we selected the original sample of 800 stars that were ranked in order of priority according to their sensitivity for planet detection in direct imaging with SPHERE. The properties of the stars that are part of the early statistical sample wererevisited, including for instance measurements from the Gaia Data Release 2. Rotation periods were derived for the vast majority of the late-type objects exploiting TESS light curves and dedicated photometric observations. Results. The properties of individual targets and of the sample as a whole are presented.
Published: 2021
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8. Constraining the Nature of the PDS 70 Protoplanets with VLTI/GRAVITY ∗

Author: Wang, J. J., Vigan, A., Lacour, S., Nowak, M., Stolker, T., De Rosa, R. J., Ginzburg, S., Gao, P., Abuter, R., Amorim, A., Asensio-Torres, R., Baubck, M., Benisty, M., Berger, J. P., Beust, H., Beuzit, J. -L., Blunt, S., Boccaletti, A., Bohn, A., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V., Cl��net, Y., Foresto, V. Coud�� du, Cridland, A., de Zeeuw, P. T., Dembet, R., Dexter, J., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Facchini, S., Gao, F., Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J., Haubois, X., Hei��el, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houll��, M., Hubert, Z., Jim��nez-Rosales, A., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Meyer, M., Kreidberg, L., Lagrange, A. -M., Lapeyr��re, V., Bouquin, J. -B. Le, L��na, P., Lutz, D., Maire, A. -L., M��nard, F., M��rand, A., Molli��re, P., Monnier, J. D., Mouillet, D., M��ller, A., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Pueyo, L., Rameau, J., Rodet, L., Rodr��guez-Coira, G., Rousset, G., Scheithauer, S., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vincent, F., von Fellenberg, S. D., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Collaboration, The GRAVITY, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)
Subjects: Gravity (chemistry), 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, Solar and stellar astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Orbit determination, Exoplanet formation, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Earth and Planetary Astrophysics (astro-ph.EP), Physics, Earth and planetary astrophysics, Astronomy, Astronomy and Astrophysics, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, Protoplanet, Long baseline interferometry 492 487 1175 932, Astrophysics - Earth and Planetary Astrophysics, Exoplanet atmospheres
Abstract: We present K-band interferometric observations of the PDS 70 protoplanets along with their host star using VLTI/GRAVITY. We obtained K-band spectra and 100 $\mu$as precision astrometry of both PDS 70 b and c in two epochs, as well as spatially resolving the hot inner disk around the star. Rejecting unstable orbits, we found a nonzero eccentricity for PDS 70 b of $0.17 \pm 0.06$, a near-circular orbit for PDS 70 c, and an orbital configuration that is consistent with the planets migrating into a 2:1 mean motion resonance. Enforcing dynamical stability, we obtained a 95% upper limit on the mass of PDS 70 b of 10 $M_\textrm{Jup}$, while the mass of PDS 70 c was unconstrained. The GRAVITY K-band spectra rules out pure blackbody models for the photospheres of both planets. Instead, the models with the most support from the data are planetary atmospheres that are dusty, but the nature of the dust is unclear. Any circumplanetary dust around these planets is not well constrained by the planets' 1-5 $\mu$m spectral energy distributions (SEDs) and requires longer wavelength data to probe with SED analysis. However with VLTI/GRAVITY, we made the first observations of a circumplanetary environment with sub-au spatial resolution, placing an upper limit of 0.3~au on the size of a bright disk around PDS 70 b., Comment: 30 pages, 9 figures, Accepted for publication in AJ
Published: 2021
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9. The GRAVITY young stellar object survey

Author: Koutoulaki, M., Garcia Lopez, R., Natta, A., Fedriani, R., Caratti o Garatti, A., Ray, T. P., Coffey, D., Brandner, W., Dougados, C., Garcia, P. J. V., Klarmann, L., Labadie, L., Perraut, K., Sanchez-Bermudez, J., Lin, C.-C., Amorim, A., Bauböck, M., Benisty, M., Berger, J. P., Buron, A., Caselli, P., Clénet, Y., Coudé du Foresto, V., de Zeeuw, P. T., Duvert, G., de Wit, W., Eckart, A., Eisenhauer, F., Filho, M., Gao, F., Gendron, E., Genzel, R., Gillessen, S., Grellmann, R., Habibi, M., Haubois, X., Haussmann, F., Henning, T., Hippler, S., Hubert, Z., Horrobin, M., Jimenez Rosales, A., Jocou, L., Kervella, P., Kolb, J., Lacour, S., Le Bouquin, J.-B., Léna, P., Linz, H., Ott, T., Paumard, T., Perrin, G., Pfuhl, O., Ramírez-Tannus, M. C., Rau, C., Rousset, G., Scheithauer, S., Shangguan, J., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., van Dishoeck, E., Vincent, F., von Fellenberg, S., Widmann, F., Wieprecht, E., Wiest, M., Wiezorrek, E., Yazici, S., Zins, G., Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)
Subjects: [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: International audience; Context. 51 Oph is a Herbig Ae/Be star that exhibits strong near-infrared CO ro-vibrational emission at 2.3 μ m, most likely originating in the innermost regions of a circumstellar disc. Aims. We aim to obtain the physical and geometrical properties of the system by spatially resolving the circumstellar environment of the inner gaseous disc. Methods. We used the second-generation Very Large Telescope Interferometer instrument GRAVITY to spatially resolve the continuum and the CO overtone emission. We obtained data over 12 baselines with the auxiliary telescopes and derive visibilities, and the differential and closure phases as a function of wavelength. We used a simple local thermal equilibrium ring model of the CO emission to reproduce the spectrum and CO line displacements. Results. Our interferometric data show that the star is marginally resolved at our spatial resolution, with a radius of ~10.58 ± 2.65 R ⊙ . The K -band continuum emission from the disc is inclined by 63° ± 1°, with a position angle of 116° ± 1°, and 4 ± 0.8 mas (0.5 ± 0.1 au) across. The visibilities increase within the CO line emission, indicating that the CO is emitted within the dust-sublimation radius. By modelling the CO bandhead spectrum, we derive that the CO is emitted from a hot ( T = 1900–2800 K) and dense ( N CO = (0.9–9) × 10 21 cm −2 ) gas. The analysis of the CO line displacement with respect to the continuum allows us to infer that the CO is emitted from a region 0.10 ± 0.02 au across, well within the dust-sublimation radius. The inclination and position angle of the CO line emitting region is consistent with that of the dusty disc. Conclusions. Our spatially resolved interferometric observations confirm the CO ro-vibrational emission within the dust-free region of the inner disc. Conventional disc models exclude the presence of CO in the dust-depleted regions of Herbig AeBe stars. Ad hoc models of the innermost disc regions, that can compute the properties of the dust-free inner disc, are therefore required.
Published: 2021
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10. The mass of Beta Pictoris c from Beta Pictoris b orbital motion

Author: Lacour, S., Wang, J. J., Rodet, L., Nowak, M., Shangguan, J., Beust, H., Lagrange, A. -M., Abuter, R., Amorim, A., Asensio-Torres, R., Benisty, M., Berger, J. -P., Blunt, S., Boccaletti, A., Bohn, A., Bolzer, M. -L., Bonnefoy, M., Bonnet, H., Bourdarot, G., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., Dembet, R., Dexter, J., de Zeeuw, P. T., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Haubois, X., Heißel, G., Henning, Th., Hinkley, S., Hippler, S., Horrobin, M., Houllé, M., Hubert, Z., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Kreidberg, L., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Lutz, D., Maire, A. -L., Mérand, A., Mollière, P., Monnier, J. D., Mouillet, D., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Rickman, E., Pueyo, L., Rameau, J., Rousset, G., Rustamkulov, Z., Samland, M., Shimizu, T., Sing, D., Stadler, J., Stolker, T., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., Young, A., and Collaboration, the GRAVITY
Subjects: Earth and Planetary Astrophysics (astro-ph.EP), Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics - Earth and Planetary Astrophysics
Abstract: We aim to demonstrate that the presence and mass of an exoplanet can now be effectively derived from the astrometry of another exoplanet. We combined previous astrometry of $\beta$ Pictoris b with a new set of observations from the GRAVITY interferometer. The orbital motion of $\beta$ Pictoris b is fit using Markov chain Monte Carlo simulations in Jacobi coordinates. The inner planet, $\beta$ Pictoris c, was also reobserved at a separation of 96\,mas, confirming the previous orbital estimations. From the astrometry of planet b only, we can (i) detect the presence of $\beta$ Pictoris c and (ii) constrain its mass to $10.04^{+4.53}_{-3.10}\,M_{\rm Jup}$. If one adds the astrometry of $\beta$ Pictoris c, the mass is narrowed down to $9.15^{+1.08}_{-1.06}\,M_{\rm Jup}$. The inclusion of radial velocity measurements does not affect the orbital parameters significantly, but it does slightly decrease the mass estimate to $8.89^{+0.75}_{-0.75}\,M_{\rm Jup}$. With a semimajor axis of $2.68\pm0.02$\,au, a period of $1221\pm15$ days, and an eccentricity of $0.32\pm0.02$, the orbital parameters of $\beta$ Pictoris c are now constrained as precisely as those of $\beta$ Pictoris b. The orbital configuration is compatible with a high-order mean-motion resonance (7:1). The impact of the resonance on the planets' dynamics would then be negligible with respect to the secular perturbations, which might have played an important role in the eccentricity excitation of the outer planet., Comment: Accepted in A&A Letter
Published: 2021
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11. The GRAVITY young stellar object survey: IV. The CO overtone emission in 51 Oph at sub-au scales

Author: GRAVITY, Collaboration, Koutoulaki, M., Lopez, R. Garcia, Natta, A., Fedriani, R., oGaratti, A. Caratti, Ray, T. P., Coffey, D., Brandner, W., Dougados, C., Garcia, P. J. V, Klarmann, L., Labadie, L., Perraut, K., Sanchez-Bermudez, J., Lin, C. -C., Amorim, A., Bauböck, M., Benisty, M., Berger, J. P., Buron, A., Caselli, P., Clénet, Y., Foresto, V. Coudé Du, De Zeeuw, P. T., Duvert, G., de Wit, W., Eckart, A., Eisenhauer, F., Filho, M., Gao, F., Gendron, E., Genzel, R., Gillessen, S., Grellmann, R., Habibi, M., Haubois, X., Haussmann, F., Henning, T., Hippler, S., Hubert, Z., Horrobin, M., Rosales, A. Jimenez, Jocou, L., Kervella, P., Kolb, J., Lacour, S., Bouquin, J. -B. Le, Léna, P., Linz, H., Ott, T., Paumard, T., Perrin, G., Pfuhl, O., Ramírez-Tannus, M. C., Rau, C., Rousset, G., Scheithauer, S., Shangguan, J., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Van Dishoeck, E., Vincent, F., Von fellenberg, S., Widmann, F., Wieprecht, E., Wiest, M., Wiezorrek, E., Yazici, S., Zins, G., Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, Dublin Institute for Advanced Studies (DIAS), School of Physics [UCD Dublin], University College Dublin [Dublin] (UCD), European Southern Observatory (ESO), Chalmers University of Technology [Gothenburg, Sweden], Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Faculdade de Engenharia da Universidade do Porto (FEUP), Universidade do Porto, Centro de Astrofísica e Gravitação (CENTRA), European Southern Observatory [Santiago] (ESO), I. Physikalisches Institut [Köln], Universität zu Köln, Instituto de Astronomía, Univ. Nacional Autónoma de México, Universidad Nacional Autónoma de México (UNAM), Institute for Astronomy, University of Hawai'i at Manoa, Universidade de Lisboa (ULISBOA), Max Planck Institute for Extraterrestrial Physics (MPE), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Sterrewacht Leiden, Universiteit Leiden [Leiden], Max-Planck-Institut für Radioastronomie (MPIFR), Department of Physics [Berkeley], University of California [Berkeley], and University of California-University of California
Subjects: Accretion, Be star, Techniques: Interferometric, Astrophysics::High Energy Astrophysical Phenomena, Overtone, Young stellar object, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Accretion Disks, 0103 physical sciences, Stars: Pre-Main Sequence, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Image resolution, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Physics, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], 010308 nuclear & particles physics, Astronomy and Astrophysics, Stars: Individual: 51 Oph, Position angle, Astrophysics - Astrophysics of Galaxies, Interferometry, Wavelength, Stars, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Earth and Planetary Astrophysics, Stars: Formation
Abstract: 51 Oph is a Herbig Ae/Be star that exhibits strong near-infrared CO ro-vibrational emission at 2.3 micron, most likely originating in the innermost regions of a circumstellar disc. We aim to obtain the physical and geometrical properties of the system by spatially resolving the circumstellar environment of the inner gaseous disc. We used the second-generation VLTI/GRAVITY to spatially resolve the continuum and the CO overtone emission. We obtained data over 12 baselines with the auxiliary telescopes and derive visibilities, and the differential and closure phases as a function of wavelength. We used a simple LTE ring model of the CO emission to reproduce the spectrum and CO line displacements. Our interferometric data show that the star is marginally resolved at our spatial resolution, with a radius of 10.58+-2.65 Rsun.The K-band continuum emission from the disc is inclined by 63+-1 deg, with a position angle of 116+-1 deg, and 4+-0.8 mas (0.5+-0.1 au) across. The visibilities increase within the CO line emission, indicating that the CO is emitted within the dust-sublimation radius.By modelling the CO bandhead spectrum, we derive that the CO is emitted from a hot (T=1900-2800 K) and dense (NCO=(0.9-9)x10^21 cm^-2) gas. The analysis of the CO line displacement with respect to the continuum allows us to infer that the CO is emitted from a region 0.10+-0.02 au across, well within the dust-sublimation radius. The inclination and position angle of the CO line emitting region is consistent with that of the dusty disc. Our spatially resolved interferometric observations confirm the CO ro-vibrational emission within the dust-free region of the inner disc. Conventional disc models exclude the presence of CO in the dust-depleted regions of Herbig AeBe stars. Ad hoc models of the innermost disc regions, that can compute the properties of the dust-free inner disc, are therefore required., Accepted in A&A
Published: 2021

12. Discovery of a planetary-mass companion within the gap of the transition disk around PDS 70

Author: Keppler, M, Benisty, M, Müller, A, Henning, T, Van Boekel, R, Cantalloube, F, Ginski, C, Van Holstein, RG, Maire, AL, Pohl, A, Samland, M, Avenhaus, H, Baudino, JL, Boccaletti, A, De Boer, J, Bonnefoy, M, Chauvin, G, Desidera, S, Langlois, M, Lazzoni, C, Marleau, GD, Mordasini, C, Pawellek, N, Stolker, T, Vigan, A, Zurlo, A, Birnstiel, T, Brandner, W, Feldt, M, Flock, M, Girard, J, Gratton, R, Hagelberg, J, Isella, A, Janson, M, Juhasz, A, Kemmer, J, Kral, Q, Lagrange, AM, Launhardt, R, Matter, A, Ménard, F, Milli, J, Mollière, P, Olofsson, J, Pérez, L, Pinilla, P, Pinte, C, Quanz, SP, Schmidt, T, Udry, S, Wahhaj, Z, Williams, JP, Buenzli, E, Cudel, M, Dominik, C, Galicher, R, Kasper, M, Lannier, J, Mesa, D, Mouillet, D, Peretti, S, Perrot, C, Salter, G, Sissa, E, Wildi, F, Abe, L, Antichi, J, Augereau, JC, Baruffolo, A, Baudoz, P, Bazzon, A, Beuzit, JL, Blanchard, P, Brems, SS, Buey, T, De Caprio, V, Carbillet, M, Carle, M, Cascone, E, Cheetham, A, Claudi, R, Costille, A, Delboulbé, A, Dohlen, K, Fantinel, D, Feautrier, P, Fusco, T, Giro, E, Gluck, L, Gry, C, Hubin, N, Hugot, E, Jaquet, M, Le Mignant, D, Llored, M, Madec, F, Magnard, Y, Martinez, P, Maurel, D, Pawellek, Nicole [0000-0002-9385-9820], and Apollo - University of Cambridge Repository
Subjects: planets and satellites: detection, stars: individual: PDS 70, radiative transfer, protoplanetary disks, scattering, Astrophysics::Solar and Stellar Astrophysics, techniques: high angular resolution, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: Young circumstellar disks are of prime interest to understand the physical and chemical conditions under which planet formation takes place. Only very few detections of planet candidates within these disks exist, and most of them are currently suspected to be disk features. In this context, the transition disk around the young star PDS 70 is of particular interest, due to its large gap identified in previous observations, indicative of ongoing planet formation. We aim to search for the presence of planets and search for disk structures indicative for disk-planet interactions and other evolutionary processes. We analyse new and archival near-infrared (NIR) images of the transition disk PDS 70 obtained with the VLT/SPHERE, VLT/NaCo and Gemini/NICI instruments in polarimetric differential imaging (PDI) and angular differential imaging (ADI) modes. We detect a point source within the gap of the disk at about 195 mas (about 22 au) projected separation. The detection is confirmed at five different epochs, in three filter bands and using different instruments. The astrometry results in an object of bound nature, with high significance. The comparison of the measured magnitudes and colours to evolutionary tracks suggests that the detection is a companion of planetary mass. We confirm the detection of a large gap of about 54 au in size within the disk in our scattered light images, and detect a signal from an inner disk component. We find that its spatial extent is very likely smaller than about 17 au in radius. The images of the outer disk show evidence of a complex azimuthal brightness distribution which may in part be explained by Rayleigh scattering from very small grains. Future observations of this system at different wavelengths and continuing astrometry will allow us to test theoretical predictions regarding planet-disk interactions, planetary atmospheres and evolutionary models.
Published: 2020
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13. Mass distribution in the Galactic Center based on interferometric astrometry of multiple stellar orbits

Author: Abuter, R., Aimar, N., Amorim, A., Ball, J., Bauböck, M., Berger, J.P., Bonnet, H., Bourdarot, G., Brandner, W., Cardoso, V., Clénet, Y., Dallilar, Y., Davies, R., de Zeeuw, P.T., Dexter, J., Drescher, A., Eisenhauer, F., Schreiber, N.M. Förster, Foschi, A., Garcia, P., Gao, F., Gendron, E., Genzel, R., Gillessen, S., Habibi, M., Haubois, X., Heißel, G., Henning, T., Hippler, S., Horrobin, M., Jochum, L., Jocou, L., Kaufer, A., Kervella, P., Lacour, S., Lapeyrère, V., Le Bouquin, J.-B., Léna, P., Lutz, D., Ott, T., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Rabien, S., Shangguan, J., Shimizu, T., Scheithauer, S., Stadler, J., Stephens, A.W., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L.J., Tristram, K.R. W., Vincent, F., von Fellenberg, S., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., and Young, A.
Subjects: Astrophysics - instrumentation and methods for astrophysics, Astrophysics and Astronomy, General Relativity and Cosmology, Astrophysics::High Energy Astrophysical Phenomena, gr-qc, astro-ph.GA, Astrophysics - astrophysics of galaxies, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Black hole physics, Instrumentation - interferometers, Space and Planetary Science, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, General relativity and quantum cosmology, Astrophysics::Galaxy Astrophysics, Galaxy - center, astro-ph.IM
Abstract: Stars orbiting the compact radio source Sgr A* in the Galactic Center serve as precision probes of the gravitational field around the closest massive black hole. In addition to adaptive optics-assisted astrometry (with NACO/VLT) and spectroscopy (with SINFONI/VLT, NIRC2/Keck and GNIRS/Gemini) over three decades, we have obtained 30–100 μas astrometry since 2017 with the four-telescope interferometric beam combiner GRAVITY/VLTI, capable of reaching a sensitivity of mK = 20 when combining data from one night. We present the simultaneous detection of several stars within the diffraction limit of a single telescope, illustrating the power of interferometry in the field. The new data for the stars S2, S29, S38, and S55 yield significant accelerations between March and July 2021, as these stars pass the pericenters of their orbits between 2018 and 2023. This allows for a high-precision determination of the gravitational potential around Sgr A*. Our data are in excellent agreement with general relativity orbits around a single central point mass, M• = 4.30 × 106 M⊙, with a precision of about ±0.25%. We improve the significance of our detection of the Schwarzschild precession in the S2 orbit to 7σ. Assuming plausible density profiles, the extended mass component inside the S2 apocenter (≈0.23″ or 2.4 × 104 RS) must be ≲3000 M⊙ (1σ), or ≲0.1% of M•. Adding the enclosed mass determinations from 13 stars orbiting Sgr A* at larger radii, the innermost radius at which the excess mass beyond Sgr A* is tentatively seen is r ≈ 2.5″ ≥ 10× the apocenter of S2. This is in full harmony with the stellar mass distribution (including stellar-mass black holes) obtained from the spatially resolved luminosity function.Key words: black hole physics / instrumentation: interferometers / Galaxy: center⋆ GRAVITY is developed in a collaboration by MPE, LESIA of Paris Observatory/CNRS/Sorbonne Université/Univ. Paris Diderot and IPAG of Université Grenoble Alpes/CNRS, MPIA, Univ. of Cologne, CENTRA – Centro de Astrofisica e Gravitação, and ESO.⋆⋆ Corresponding authors: S. Gillessen (e-mail: ste@mpe.mpg.de), F. Widmann (e-mail: fwidmann@mpe.mpg.de), and G. Heißel (e-mail: gernot.heissel@obspm.fr). The stars orbiting the compact radio source Sgr A* in the Galactic Centre are precision probes of the gravitational field around the closest massive black hole. In addition to adaptive optics assisted astrometry (with NACO / VLT) and spectroscopy (with SINFONI / VLT, NIRC2 / Keck and GNIRS / Gemini) over three decades, since 2016/2017 we have obtained 30-100 mu-as astrometry with the four-telescope interferometric beam combiner GRAVITY / VLTI reaching a sensitivity of mK = 20 when combining data from one night. We present the simultaneous detection of several stars within the diffraction limit of a single telescope, illustrating the power of interferometry. The new data for the stars S2, S29, S38 and S55 yield significant accelerations between March and July 2021, as these stars pass the pericenters of their orbits between 2018 and 2023. This allows for a high-precision determination of the gravitational potential around Sgr A*. Our data are in excellent agreement with general relativity orbits around a single central point mass, M = 4.30 x 10^6 M_sun with a precision of about +-0.25%. We improve the significance of our detection of the Schwarzschild precession in the S2 orbit to 7 sigma. Assuming plausible density profiles, an extended mass component inside S2's apocentre (= 0.23" or 2.4 x 10^4 R_S) must be 3000 M_sun (1 sigma), or 0.1% of M. Adding the enclosed mass determinations from 13 stars orbiting Sgr A* at larger radii, the innermost radius at which the excess mass beyond Sgr A* tentatively is seen is r = 2.5" >= 10x the apocentre of S2. This is in full harmony with the stellar mass distribution (including stellar-mass black holes) obtained from the spatially resolved luminosity function.
Published: 2022
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14. GRAVITY K-band spectroscopy of HD 206893 B

Author: Kammerer, J., Lacour, S., Stolker, T., Molli��re, P., Sing, D. K., Nasedkin, E., Kervella, P., Wang, J. J., Ward-Duong, K., Nowak, M., Abuter, R., Amorim, A., Asensio-Torres, R., Baub��ck, M., Benisty, M., Berger, J. -P., Beust, H., Blunt, S., Boccaletti, A., Bohn, A., Bolzer, M. -L., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V., Cl��net, Y., Foresto, V. Coud�� du, Cridland, A., Dembet, R., Dexter, J., de Zeeuw, P. T., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Girard, J., Haubois, X., Hei��el, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houll��, M., Hubert, Z., Jocou, L., Keppler, M., Kreidberg, L., Lagrange, A. -M., Lapeyr��re, V., Bouquin, J. -B. Le, L��na, P., Lutz, D., Maire, A. -L., M��rand, A., Monnier, J. D., Mouillet, D., M��ller, A., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Pueyo, L., Rameau, J., Rodet, L., Rousset, G., Rustamkulov, Z., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., and Collaboration, GRAVITY
Subjects: Interferometric, Proper motion, Extinction (astronomy), Brown dwarf, FOS: Physical sciences, Orbital eccentricity, Astrophysics, Astrophysic, Astrophysics::Solar and Stellar Astrophysics, Solar and Stellar Astrophysics, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Gaseous Planets, Earth and Planetary Astrophysics (astro-ph.EP), Physics, Orbital elements, Debris disk, Planets and Satellites: Atmospheres, Astronomy and Astrophysics, Techniques, Exoplanet, Radial velocity, Detection, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Earth and Planetary Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract: We aim to reveal the nature of the reddest known substellar companion HD 206893 B by studying its near-infrared colors and spectral morphology and by investigating its orbital motion. We fit atmospheric models for giant planets and brown dwarfs and perform spectral retrievals with petitRADTRANS and ATMO on the observed GRAVITY, SPHERE, and GPI spectra of HD 206893 B. To recover its unusual spectral features, we include additional extinction by high-altitude dust clouds made of enstatite grains in the atmospheric model fits. We also infer the orbital parameters of HD 206893 B by combining the $\sim 100~��\text{as}$ precision astrometry from GRAVITY with data from the literature and constrain the mass and position of HD 206893 C based on the Gaia proper motion anomaly of the system. The extremely red color and the very shallow $1.4~��\text{m}$ water absorption feature of HD 206893 B can be fit well with the adapted atmospheric models and spectral retrievals. Altogether, our analysis suggests an age of $\sim 3$-$300~\text{Myr}$ and a mass of $\sim 5$-$30~\text{M}_\text{Jup}$ for HD 206893 B, which is consistent with previous estimates but extends the parameter space to younger and lower-mass objects. The GRAVITY astrometry points to an eccentric orbit ($e = 0.29^{+0.06}_{-0.11}$) with a mutual inclination of $< 34.4~\text{deg}$ with respect to the debris disk of the system. While HD 206893 B could in principle be a planetary-mass companion, this possibility hinges on the unknown influence of the inner companion on the mass estimate of $10^{+5}_{-4}~\text{M}_\text{Jup}$ from radial velocity and Gaia as well as a relatively small but significant Argus moving group membership probability of $\sim 61\%$. However, we find that if the mass of HD 206893 B is $< 30~\text{M}_\text{Jup}$, then the inner companion HD 206893 C should have a mass between $\sim 8$-$15~\text{M}_\text{Jup}$., 28 pages, 19 figures, accepted for publication in A&A
Published: 2021
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15. The GRAVITY Young Stellar Object survey

Author: Collaboration, Gravity, Perraut, K., Labadie, L., Lazareff, B., Klarmann, L., Segura-Cox, D., Benisty, M., Bouvier, J., Brandner, W., Caratti O Garatti, A., Caselli, P., Dougados, C., Garcia, P., Garcia-Lopez, R., Kendrew, S., Koutoulaki, M., Kervella, P., Lin, C.-C., Pineda, J., Sanchez-Bermudez, J., Van Dishoeck, E., Abuter, R., Amorim, A., Berger, J.-P., BONNET, H., Buron, A., Cantalloube, F., Clénet, Y., Coudé Du Foresto, V., Dexter, J., De Zeeuw, P. T., Duvert, G., Eckart, A., Eisenhauer, F., Eupen, F., Gao, F., Gendron, E., Genzel, R., Gillessen, S., Gordo, P., Grellmann, R., Haubois, X., Haussmann, F., Henning, T., Hippler, S., Horrobin, M., Hubert, Z., Jocou, L., Lacour, S., Le Bouquin, J.-B., Léna, P., Mérand, A., Ott, T., Paumard, T., Perrin, G., Pfuhl, O., Rabien, S., Ray, T., Rau, C., Rousset, G., Scheithauer, S., Straub, O., Straubmeier, C., Sturm, E., Vincent, F., Waisberg, I., Wank, I., Widmann, F., Wieprecht, E., Wiest, M., Wiezorrek, E., Woillez, J., Yazici, S., Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, Max-Planck-Institut für Extraterrestrische Physik (MPE), LIttoral ENvironnement et Sociétés - UMR 7266 (LIENSs), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), National Tsing Hua University [Hsinchu] (NTHU), Laboratoire de Radiopathologie (LRP), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de la Santé et de la Recherche Médicale (INSERM), European Southern Observatory (ESO), Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Institute Patology and Imunology Molecular, Fac Ciencias, Universidade do Porto [Porto], Département de Chimie Moléculaire (DCM), Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Radioastronomie (MPIFR), Max Planck Institute for Extraterrestrial Physics (MPE), Physikalisches Institut [Köln], Universität zu Köln, Galaxies, Etoiles, Physique, Instrumentation (GEPI), PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Institut Européen des membranes (IEM), Université de Montpellier (UM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS), Diamond Light Source, Harwell, Berks, England, AUTRES, Observatoire de Paris - Site de Paris (OP), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology [2007-2019] (Grenoble INP [2007-2019])-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology [2007-2019] (Grenoble INP [2007-2019])-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), LIttoral ENvironnement et Sociétés - UMRi 7266 (LIENSs), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de la Santé et de la Recherche Médicale (INSERM), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), and Universidade do Porto
Subjects: infrared: ISM, stars: formation, techniques: interferometric, Astrophysics::Solar and Stellar Astrophysics, techniques: high angular resolution, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], circumstellar matter, Astrophysics::Galaxy Astrophysics
Abstract: International audience; Context. The formation and the evolution of protoplanetary disks are important stages in the lifetime of stars. Terrestrial planets form or migrate within the innermost regions of these protoplanetary disks and so, the processes of disk evolution and planet formation are intrinsically linked. Studies of the dust distribution, composition, and evolution of these regions are crucial to understanding planet formation. Aims: We built a homogeneous observational dataset of Herbig Ae/Be disks with the aim of spatially resolving the sub au-scale region to gain a statistical understanding of their morphological and compositional properties, in addition to looking for correlations with stellar parameters, such as luminosity, mass, and age. Methods: We observed 27 Herbig Ae/Be stars with the GRAVITY instrument installed at the combined focus of the Very Large Telescope Interferometer (VLTI) and operating in the near-infrared K-band, focused on the K-band thermal continuum, which corresponds to stellar flux reprocessed by the dust grains. Our sample covers a large range of effective temperatures, luminosities, masses, and ages for the intermediate-mass star population. The circumstellar disks in our sample also cover a range of various properties in terms of reprocessed flux, flared or flat morphology, and gaps. We developed semi-physical geometrical models to fit our interferometric data. Results: Our best-fit models correspond to smooth and wide rings that support previous findings in the H-band, implying that wedge-shaped rims at the dust sublimation edge are favored. The measured closure phases are generally non-null with a median value of 10°, indicating spatial asymmetries of the intensity distributions. Multi-size grain populations could explain the closure phase ranges below 20-25° but other scenarios should be invoked to explain the largest ones. Our measurements extend the Radius-Luminosity relation to 104 L⊙ luminosity values and confirm the significant spread around the mean relation observed by PIONIER in the H-band. Gapped sources exhibit a large N-to-K band size ratio and large values of this ratio are only observed for the members of our sample that would be older than 1 Ma, less massive, and with lower luminosity. In the mass range of 2 M⊙, we do observe a correlation in the increase of the relative age with the transition from group II to group I, and an increase of the N-to-K size ratio. However, the size of the current sample does not yet permit us to invoke a clear, universal evolution mechanism across the Herbig Ae/Be mass range. The measured locations of the K-band emission in our sample suggest that these disks might be structured by forming young planets, rather than by depletion due to EUV, FUV, and X-ray photo-evaporation. GTO programs with run ID: 0103.C-0347; 0102.C-0408; 0101.C-0311; 0100.C-0278; 099.C-0667.
Published: 2019
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16. Images at the Highest Angular Resolution with GRAVITY: The Case of η Carinae

Author: Abuter, R., Accardo, M., Adler, T., Amorim, A., Anugu, N., Ávila, G., Bauböck, M., Benisty, M., Berger, J.-P., Bestenlehner, J. M., Beust, H., Blind, N., Bonnefoy, M., BONNET, H., Bourget, P., Bouvier, J., Brandner, W., Brast, R., Buron, A., Burtscher, L., Cantalloube, F., Caratti O Garatti, A., Caselli, P., Cassaing, F., Chapron, F., Charnay, B., Choquet, E., Clénet, Y., Collin, C., Coudé Du Foresto, V., Davies, R., Deen, C., Delplancke-Ströbele, F., Dembet, R., Derie, F., de Wit, W.-J., Dexter, J., De Zeeuw, T., Dougados, C., Dubus, G., Duvert, G., Ebert, M., Eckart, A., Eisenhauer, F., Esselborn, M., Eupen, F., Fédou, P., Ferreira, M. C., Finger, G., Förster Schreiber, N. M., Gao, F., García Dabó, C. E., Garcia Lopez, R., Garcia, P. J. V., Gendron, É., Genzel, R., Gerhard, O., Gil, J. P., Gillessen, S., Gonté, F., Gordo, P., Gratadour, D., Greenbaum, A., Grellmann, R., Grözinger, U., Guajardo, P., Guieu, S., Habibi, M., Haguenauer, P., Hans, O., Haubois, X., Haug, M., Haußmann, F., Henning, T., Hippler, S., Hönig, S. F., Horrobin, M., Huber, A., Hubert, Z., Hubin, N., Hummel, C. A., Jakob, G., Janssen, A., Jimenez Rosales, A., Jochum, L., Jocou, L., Kammerer, J., Karl, M., Kaufer, A., Kellner, S., Kendrew, S., Kern, L., Kervella, P., Kiekebusch, M., Kishimoto, M., Klarmann, L., Klein, R., Köhler, R., Kok, Y., Kolb, J., Koutoulaki, M., Kulas, M., Labadie, L., Lacour, S., Lagrange, A.-M., Lapeyrère, V., Laun, W., Lazareff, B., Le Bouquin, J.-B., Léna, P., Lenzen, R., Lévêque, S., Lin, C.-C., Lippa, M., Lutz, D., Magnard, Y., Maire, A.-L., Mehrgan, L., Mérand, A., Millour, F., Mollière, P., Moulin, T., Müller, A., Müller, E., Müller, F., Netzer, H., Neumann, U., Nowak, M., Oberti, S., Ott, T., Pallanca, L., Panduro, J., Pasquini, L., Paumard, T., Percheron, I., Perraut, K., Perrin, G., Peterson, B. M., Petrucci, P.-O., Pflüger, A., Pfuhl, O., Phan Duc, T., Pineda, J. E., Plewa, P. m., Popovic, D., Pott, J.-U., Prieto, A., Pueyo, L., Rabien, S., Ramírez, A., Ramos, J. R., Rau, C., Ray, T., Riquelme, M., Rodríguez-Coira, G., Rohloff, R.-R., Rouan, D., Rousset, G., Sanchez-Bermudez, J., Schartmann, M., Scheithauer, S., Schöller, M., Schuhler, N., Segura-Cox, D., Shangguan, J., Shimizu, T. T., Spyromilio, J., Sternberg, A., Stock, M. R., Straub, O., Straubmeier, C., Sturm, E., Suárez Valles, M., Tacconi, L. J., Thi, W.-F., Tristram, K. R. W., Valenzuela, J. J., Van Boekel, R., Van Dishoeck, E. F., Vermot, P., Vincent, F., Von fellenberg, S., Waisberg, I., Wang, J. J., Wank, I., Weber, J., Weigelt, G., Widmann, F., Wieprecht, E., Wiest, M., Wiezorrek, E., Wittkowski, M., Woillez, J., Wolff, B., Yang, P., Yazici, S., Ziegler, D., Zins, G., and European Southern Observatory (ESO)
Subjects: [SDU]Sciences of the Universe [physics], Astrophysics::High Energy Astrophysical Phenomena, 0103 physical sciences, Astrophysics::Instrumentation and Methods for Astrophysics, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, 01 natural sciences
Abstract: The main goal of an interferometer is to probe the physics of astronomical objects at the highest possible angular resolution. The most intuitive way of doing this is by reconstructing images from the interferometric data. GRAVITY at the Very Large Telescope Interferometer (VLTI) has proven to be a fantastic instrument in this endeavour. In this article, we describe the reconstruction of the wind-wind collision cavity of the massive binary η Car with GRAVITY across two spectral lines: HeI and Brγ., Published in The Messenger vol. 178, pp. 31-33, December 2019.
Published: 2019
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17. High-fidelity Imaging of the Inner AU Mic Debris Disk: Evidence of Differential Wind Sculpting?

Author: Molaverdikhani, K., Trifonov, T., Mollière, P., Frankel, N., Messina, S., Biller, B. A., Roux, A., Damasso, M., Del Sordo, F., Brandner, W., Kervella, P., Mugnier, L., Romero, C., Sozzetti, A., Antichi, J., Huby, E., N’Diaye, M., Kitzmann, D., Tang, Y. W., Habart, E., Beck, T. L., Potier, A., Singh, G., Di Folco, E., Péricaud, J., Dutrey, A., Chapillon, E., Guilloteau, S., Piétu, V., Pawellek, N., Brown, S., Buey, T., Moeller-Nilsson, O., Stolker, T., Hunziker, S., Abe, L., Avenhaus, H., Baruffolo, A., Bazzon, A., Costille, A., Daban, J.-B., Downing, M., Engler, N., Gisler, D., Hubin, N., Puget, P., Quanz, S. P., Roelfsema, R., Salasnich, B., Siebenmorgen, R., Suarez, M., Szulágyi, J., Thalmann, Ch., Pohl, A., Fantinel, D., Maurel, D., Origné, A., Petit, C., Rigal, F., Girard, J. H., Mouillet, D., Dohlen, K., Snik, F., Keller, C. U., Ginski, C., Stam, D. M., Wahhaj, Z., Kasper, M., Schmid, H. M., Perret, D., Dominik, C., Turatto, M., Beuzit, J.-L., Keppler, M., Rodet, L., Charnay, B., Bae, J., De Boer, J., Müller, A., Pairet, B., Antoniucci, S., Brown Sevilla, S., Cascone, E., Claudi, R. U., Lagadec, E., Martinez, P., Meunier, N., Petrus, S., Pinte, C., Rochat, S., Sauvage, J.-F., Peretti, S., Ségransan, D., Lavie, B., Baudino, J.-L., Janson, M., Heng, Kevin, Udry, S., Daemgen, S., Le Coroller, H., Samland, M., Carbillet, M., Carle, M., Hugot, E., Magnard, Y., Moulin, T., Pavlov, A., Pragt, J., Rabou, P., Rousset, G., Sevin, A., Soenke, C., Stadler, E., Weber, L., Wildi, F., Bhowmik, T., Thébault, P., Kral, Q., Mazoyer, J., van Holstein, R. G., Baudoz, P., Galicher, R., Olofsson, J., Pantin, E., Perrot, C., Mesa, D., Langlois, M., Garufi, A., Gratton, R., Desidera, S., D'Orazi, V., Flasseur, O., Barbieri, M., Benisty, M., Henning, Th., Ligi, R., Sissa, E., Vigan, A., Zurlo, A., Bonnefoy, M., Cantalloube, F., Chauvin, G., Cheetham, A. C., De Caprio, V., Delorme, P., Feldt, M., Fusco, T., Gluck, L., Hagelberg, J., Lazzoni, C., Madec, F., Maire, A.-L., Ménard, F., Meyer, M. R., Ramos, J., Rickman, E. L., Rouan, D., Schmidt, T., van der Plas, G., D’Orazi, V., De Caprio, V, Van der Plas, G, Wisniewski, John P., Kowalski, Adam F., Davenport, James R. A., Schneider, Glenn, Grady, Carol A., Hebb, Leslie, Lawson, Kellen D., Augereau, Jean-Charles, Boccaletti, A., Brown, Alexander, Debes, John H., Gaspar, Andras, Henning, Thomas K., Hines, Dean C., Kuchner, Marc J., Lagrange, Anne-Marie, Milli, Julien, Sezestre, Elie, Stark, Christopher C., Thalmann, Christian, Wisniewski, John, Kowalski, Adam, Davenport, James, Grady, Carol, Lawson, Kellen, Debes, John, Henning, Thomas, Hines, Dean, Kuchner, Marc, Stark, Christopher, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: planets and satellites: detection, 010504 meteorology & atmospheric sciences, planets and satellites: dynamical evolution and stability, stars: individual: HD 117214, stars: individual: AB Aur, techniques: image processing, Astrophysics, M dwarf stars, 01 natural sciences, stars: individual: HD 19467, accretion, Debris disks, Astrophysics::Solar and Stellar Astrophysics, infrared: planetary systems, 010303 astronomy & astrophysics, instrumentation: spectrographs, Physics, Earth and Planetary Astrophysics (astro-ph.EP), planets and satellites: atmospheres, [PHYS]Physics [physics], planet-disk interactions, accretion disks, stars: individual: HD 32297, protoplanetary disks, stars: individual: Proxima, Exoplanet, Astrophysics - Solar and Stellar Astrophysics, binaries: general, techniques: imaging spectroscopy, techniques: interferometric, stars individual: HIP 65875, planets and satellites: individual: Proxima c, Astrophysics::Earth and Planetary Astrophysics, methods: observational, radio lines: stars, binaries: spectroscopic, brown dwarfs, (stars:) planetary systems, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Brown dwarf, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, stars: pre-main sequence, instrumentation: adaptive optics, planets and satellites: terrestrial planets, stars: individual: PDS70, instrumentation: high angular resolution, 0103 physical sciences, planetary systems, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Debris disk, polarization, HD 163296, Stellar rotation, Starspot, techniques: high angular resolution, Astronomy and Astrophysics, Planetary system, methods: data analysis, binaries: visual, Starspots, techniques: polarimetric, Polar wind, Space and Planetary Science, Circumstellar disks, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Heliosphere, Astrophysics - Earth and Planetary Astrophysics
Abstract: The Astrophysical Journal Letters, 883 (1), ISSN:1967-2014, ISSN:2041-8213
Published: 2019
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18. Multiple Star Systems in the Orion Nebula

Author: Abuter, R., Accardo, M., Adler, T., Amorim, A., Anugu, N., Ávila, G., Bauböck, M., Benisty, M., Berger, J.-P., Bestenlehner, J. M., Beust, H., Blind, N., Bonnefoy, M., BONNET, H., Bourget, P., Bouvier, J., Brandner, W., Brast, R., Buron, A., Burtscher, L., Cantalloube, F., Caratti O Garatti, A., Caselli, P., Cassaing, F., Chapron, F., Charnay, B., Choquet, E., Clénet, Y., Collin, C., Coudé Du Foresto, V., Davies, R., Deen, C., Delplancke-Ströbele, F., Dembet, R., Derie, F., de Wit, W.-J., Dexter, J., De Zeeuw, T., Dougados, C., Dubus, G., Duvert, G., Ebert, M., Eckart, A., Eisenhauer, F., Esselborn, M., Eupen, F., Fédou, P., Ferreira, M. C., Finger, G., Förster Schreiber, N. M., Gao, F., García Dabó, C. E., Garcia Lopez, R., Garcia, P. J. V., Gendron, É., Genzel, R., Gerhard, O., Gil, J. P., Gillessen, S., Gonté, F., Gordo, P., Gratadour, D., Greenbaum, A., Grellmann, R., Grözinger, U., Guajardo, P., Guieu, S., Habibi, M., Haguenauer, P., Hans, O., Haubois, X., Haug, M., Haußmann, F., Henning, T., Hippler, S., Hönig, S. F., Horrobin, M., Huber, A., Hubert, Z., Hubin, N., Hummel, C. A., Jakob, G., Janssen, A., Jimenez Rosales, A., Jochum, L., Jocou, L., Kammerer, J., Karl, M., Kaufer, A., Kellner, S., Kendrew, S., Kern, L., Kervella, P., Kiekebusch, M., Kishimoto, M., Klarmann, L., Klein, R., Köhler, R., Kok, Y., Kolb, J., Koutoulaki, M., Kulas, M., Labadie, L., Lacour, S., Lagrange, A.-M., Lapeyrère, V., Laun, W., Lazareff, B., Le Bouquin, J.-B., Léna, P., Lenzen, R., Lévêque, S., Lin, C.-C., Lippa, M., Lutz, D., Magnard, Y., Maire, A.-L., Mehrgan, L., Mérand, A., Millour, F., Mollière, P., Moulin, T., Müller, A., Müller, E., Müller, F., Netzer, H., Neumann, U., Nowak, M., Oberti, S., Ott, T., Pallanca, L., Panduro, J., Pasquini, L., Paumard, T., Percheron, I., Perraut, K., Perrin, G., Peterson, B. M., Petrucci, P.-O., Pflüger, A., Pfuhl, O., Phan Duc, T., Pineda, J. E., Plewa, P. m., Popovic, D., Pott, J.-U., Prieto, A., Pueyo, L., Rabien, S., Ramírez, A., Ramos, J. R., Rau, C., Ray, T., Riquelme, M., Rodríguez-Coira, G., Rohloff, R.-R., Rouan, D., Rousset, G., Sanchez-Bermudez, J., Schartmann, M., Scheithauer, S., Schöller, M., Schuhler, N., Segura-Cox, D., Shangguan, J., Shimizu, T. T., Spyromilio, J., Sternberg, A., Stock, M. R., Straub, O., Straubmeier, C., Sturm, E., Suárez Valles, M., Tacconi, L. J., Thi, W.-F., Tristram, K. R. W., Valenzuela, J. J., Van Boekel, R., Van Dishoeck, E. F., Vermot, P., Vincent, F., Von fellenberg, S., Waisberg, I., Wang, J. J., Wank, I., Weber, J., Weigelt, G., Widmann, F., Wieprecht, E., Wiest, M., Wiezorrek, E., Wittkowski, M., Woillez, J., Wolff, B., Yang, P., Yazici, S., Ziegler, D., Zins, G., and European Southern Observatory (ESO)
Subjects: [SDU]Sciences of the Universe [physics], Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: GRAVITY observations reveal that most massive stars in the Orion Trapezium cluster live in multiple systems. Our deep, milliarcsecond-resolution interferometry fills the gap at 1–100 astronomical units (au), which is not accessible to traditional imaging and spectroscopy, but is crucial to uncovering the mystery of high-mass star formation.The new observations find a significantly higher companion fraction than earlier studies of mostly OB associations. The observed distribution of mass ratios declines steeply with mass and follows a Salpeter power-law initial mass function. The observations therefore exclude stellar mergers as the dominant formation mechanism for massive stars in Orion., Published in The Messenger vol. 178, pp. 36-38, December 2019.
Published: 2019
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19. Spatially Resolving the Inner Gaseous Disc of the Herbig Star 51 Oph through its CO Ro-vibration Emission

Author: Abuter, R., Accardo, M., Adler, T., Amorim, A., Anugu, N., Ávila, G., Bauböck, M., Benisty, M., Berger, J.-P., Bestenlehner, J. M., Beust, H., Blind, N., Bonnefoy, M., BONNET, H., Bourget, P., Bouvier, J., Brandner, W., Brast, R., Buron, A., Burtscher, L., Cantalloube, F., Caratti O Garatti, A., Caselli, P., Cassaing, F., Chapron, F., Charnay, B., Choquet, E., Clénet, Y., Collin, C., Coudé Du Foresto, V., Davies, R., Deen, C., Delplancke-Ströbele, F., Dembet, R., Derie, F., de Wit, W.-J., Dexter, J., De Zeeuw, T., Dougados, C., Dubus, G., Duvert, G., Ebert, M., Eckart, A., Eisenhauer, F., Esselborn, M., Eupen, F., Fédou, P., Ferreira, M. C., Finger, G., Förster Schreiber, N. M., Gao, F., García Dabó, C. E., Garcia Lopez, R., Garcia, P. J. V., Gendron, É., Genzel, R., Gerhard, O., Gil, J. P., Gillessen, S., Gonté, F., Gordo, P., Gratadour, D., Greenbaum, A., Grellmann, R., Grözinger, U., Guajardo, P., Guieu, S., Habibi, M., Haguenauer, P., Hans, O., Haubois, X., Haug, M., Haußmann, F., Henning, T., Hippler, S., Hönig, S. F., Horrobin, M., Huber, A., Hubert, Z., Hubin, N., Hummel, C. A., Jakob, G., Janssen, A., Jimenez Rosales, A., Jochum, L., Jocou, L., Kammerer, J., Karl, M., Kaufer, A., Kellner, S., Kendrew, S., Kern, L., Kervella, P., Kiekebusch, M., Kishimoto, M., Klarmann, L., Klein, R., Köhler, R., Kok, Y., Kolb, J., Koutoulaki, M., Kulas, M., Labadie, L., Lacour, S., Lagrange, A.-M., Lapeyrère, V., Laun, W., Lazareff, B., Le Bouquin, J.-B., Léna, P., Lenzen, R., Lévêque, S., Lin, C.-C., Lippa, M., Lutz, D., Magnard, Y., Maire, A.-L., Mehrgan, L., Mérand, A., Millour, F., Mollière, P., Moulin, T., Müller, A., Müller, E., Müller, F., Netzer, H., Neumann, U., Nowak, M., Oberti, S., Ott, T., Pallanca, L., Panduro, J., Pasquini, L., Paumard, T., Percheron, I., Perraut, K., Perrin, G., Peterson, B. M., Petrucci, P.-O., Pflüger, A., Pfuhl, O., Phan Duc, T., Pineda, J. E., Plewa, P. m., Popovic, D., Pott, J.-U., Prieto, A., Pueyo, L., Rabien, S., Ramírez, A., Ramos, J. R., Rau, C., Ray, T., Riquelme, M., Rodríguez-Coira, G., Rohloff, R.-R., Rouan, D., Rousset, G., Sanchez-Bermudez, J., Schartmann, M., Scheithauer, S., Schöller, M., Schuhler, N., Segura-Cox, D., Shangguan, J., Shimizu, T. T., Spyromilio, J., Sternberg, A., Stock, M. R., Straub, O., Straubmeier, C., Sturm, E., Suárez Valles, M., Tacconi, L. J., Thi, W.-F., Tristram, K. R. W., Valenzuela, J. J., Van Boekel, R., Van Dishoeck, E. F., Vermot, P., Vincent, F., Von fellenberg, S., Waisberg, I., Wang, J. J., Wank, I., Weber, J., Weigelt, G., Widmann, F., Wieprecht, E., Wiest, M., Wiezorrek, E., Wittkowski, M., Woillez, J., Wolff, B., Yang, P., Yazici, S., Ziegler, D., Zins, G., and European Southern Observatory (ESO)
Subjects: [SDU]Sciences of the Universe [physics], Astrophysics::Instrumentation and Methods for Astrophysics, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: Near-infrared interferometry gives us the opportunity to spatially resolve the circumstellar environment of young stars at sub-astronomical-unit (au) scales, which a standalone telescope could not reach. In particular, the sensitivity of GRAVITY on the VLTI allows us to spatially resolve the CO overtone emission at 2.3 microns. In this article, we present a new method of using the model of the CO spectrum to reconstruct the differential phase signal and extract the geometry and size of the emitting region., Published in The Messenger vol. 178, pp. 40-42, December 2019.
Published: 2019
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20. Detecting Weather Patterns on Low-Gravity Brown Dwarfs

Author: Vos, J., Biller, B., Bonavita, M., Eriksson, S., Liu, M., Best, W., Metchev, S., Radigan, J., Allers, K., Janson, M., Buenzli, E., Dupuy, T., Bonnefoy, M., Manjavacas, E., Brandner, W., Crossfield, I., Deacon, N., Henning, T., Homeier, D., Kopytova, T., and Schlieder, J.
Subjects: Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: Photometric variability monitoring is sensitive to atmospheric features as they rotate in and out of view, allowing us to probe the presence of features caused by inhomogeneous clouds and temperature fluctuations. Periodic variability has been detected in L and T brown dwarfs, and more recently in a small sample of free-floating, planetary-mass objects. These young, low-gravity objects share a striking resemblance with the directly-imaged planets and can be studied in far greater detail in the absence of a bright host star. The large amplitudes observed in this small sample of low-gravity objects suggests that variability may be enhanced for the exoplanet analogues. We have recently carried out the first large survey for weather patterns on low-gravity brown dwarfs and exoplanet analogues. I will present the results of this survey and discuss what we have learned about the role of surface gravity in variability properties.
Published: 2019

21. An Image of the Dust Sublimation Region in the Nucleus of NGC 1068

Author: Abuter, R., Accardo, M., Adler, T., Amorim, A., Anugu, N., Ávila, G., Bauböck, M., Benisty, M., Berger, J.-P., Bestenlehner, J. M., Beust, H., Blind, N., Bonnefoy, M., BONNET, H., Bourget, P., Bouvier, J., Brandner, W., Brast, R., Buron, A., Burtscher, L., Cantalloube, F., Caratti O Garatti, A., Caselli, P., Cassaing, F., Chapron, F., Charnay, B., Choquet, E., Clénet, Y., Collin, C., Coudé Du Foresto, V., Davies, R., Deen, C., Delplancke-Ströbele, F., Dembet, R., Derie, F., de Wit, W.-J., Dexter, J., De Zeeuw, T., Dougados, C., Dubus, G., Duvert, G., Ebert, M., Eckart, A., Eisenhauer, F., Esselborn, M., Eupen, F., Fédou, P., Ferreira, M. C., Finger, G., Förster Schreiber, N. M., Gao, F., García Dabó, C. E., Garcia Lopez, R., Garcia, P. J. V., Gendron, É., Genzel, R., Gerhard, O., Gil, J. P., Gillessen, S., Gonté, F., Gordo, P., Gratadour, D., Greenbaum, A., Grellmann, R., Grözinger, U., Guajardo, P., Guieu, S., Habibi, M., Haguenauer, P., Hans, O., Haubois, X., Haug, M., Haußmann, F., Henning, T., Hippler, S., Hönig, S. F., Horrobin, M., Huber, A., Hubert, Z., Hubin, N., Hummel, C. A., Jakob, G., Janssen, A., Jimenez Rosales, A., Jochum, L., Jocou, L., Kammerer, J., Karl, M., Kaufer, A., Kellner, S., Kendrew, S., Kern, L., Kervella, P., Kiekebusch, M., Kishimoto, M., Klarmann, L., Klein, R., Köhler, R., Kok, Y., Kolb, J., Koutoulaki, M., Kulas, M., Labadie, L., Lacour, S., Lagrange, A.-M., Lapeyrère, V., Laun, W., Lazareff, B., Le Bouquin, J.-B., Léna, P., Lenzen, R., Lévêque, S., Lin, C.-C., Lippa, M., Lutz, D., Magnard, Y., Maire, A.-L., Mehrgan, L., Mérand, A., Millour, F., Mollière, P., Moulin, T., Müller, A., Müller, E., Müller, F., Netzer, H., Neumann, U., Nowak, M., Oberti, S., Ott, T., Pallanca, L., Panduro, J., Pasquini, L., Paumard, T., Percheron, I., Perraut, K., Perrin, G., Peterson, B. M., Petrucci, P.-O., Pflüger, A., Pfuhl, O., Phan Duc, T., Pineda, J. E., Plewa, P. m., Popovic, D., Pott, J.-U., Prieto, A., Pueyo, L., Rabien, S., Ramírez, A., Ramos, J. R., Rau, C., Ray, T., Riquelme, M., Rodríguez-Coira, G., Rohloff, R.-R., Rouan, D., Rousset, G., Sanchez-Bermudez, J., Schartmann, M., Scheithauer, S., Schöller, M., Schuhler, N., Segura-Cox, D., Shangguan, J., Shimizu, T. T., Spyromilio, J., Sternberg, A., Stock, M. R., Straub, O., Straubmeier, C., Sturm, E., Suárez Valles, M., Tacconi, L. J., Thi, W.-F., Tristram, K. R. W., Valenzuela, J. J., Van Boekel, R., Van Dishoeck, E. F., Vermot, P., Vincent, F., Von fellenberg, S., Waisberg, I., Wang, J. J., Wank, I., Weber, J., Weigelt, G., Widmann, F., Wieprecht, E., Wiest, M., Wiezorrek, E., Wittkowski, M., Woillez, J., Wolff, B., Yang, P., Yazici, S., Ziegler, D., Zins, G., Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU]Sciences of the Universe [physics], Astrophysics::High Energy Astrophysical Phenomena, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 010303 astronomy & astrophysics, 01 natural sciences, Astrophysics::Galaxy Astrophysics
Abstract: The superb resolution of the Very Large Telescope Interferometer (VLTI) and the unrivalled sensitivity of GRAVITY have allowed us to reconstruct the first detailed image of the dust sublimation region in an active galaxy. In the nearby archetypal Seyfert 2 galaxy NGC 1068, the 2 µm continuum emission traces a highly inclined thin ring-like structure with a radius of 0.24 pc. The observed morphology challenges the picture of a geometrically and optically thick torus., Published in The Messenger vol. 178, pp. 24-26, December 2019.
Published: 2019
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22. Probing the Discs of Herbig Ae/Be Stars at Terrestrial Orbits

Author: Abuter, R., Accardo, M., Adler, T., Amorim, A., Anugu, N., Ávila, G., Bauböck, M., Benisty, M., Berger, J.-P., Bestenlehner, J. M., Beust, H., Blind, N., Bonnefoy, M., BONNET, H., Bourget, P., Bouvier, J., Brandner, W., Brast, R., Buron, A., Burtscher, L., Cantalloube, F., Caratti O Garatti, A., Caselli, P., Cassaing, F., Chapron, F., Charnay, B., Choquet, E., Clénet, Y., Collin, C., Coudé Du Foresto, V., Davies, R., Deen, C., Delplancke-Ströbele, F., Dembet, R., Derie, F., de Wit, W.-J., Dexter, J., De Zeeuw, T., Dougados, C., Dubus, G., Duvert, G., Ebert, M., Eckart, A., Eisenhauer, F., Esselborn, M., Eupen, F., Fédou, P., Ferreira, M. C., Finger, G., Förster Schreiber, N. M., Gao, F., García Dabó, C. E., Garcia Lopez, R., Garcia, P. J. V., Gendron, É., Genzel, R., Gerhard, O., Gil, J. P., Gillessen, S., Gonté, F., Gordo, P., Gratadour, D., Greenbaum, A., Grellmann, R., Grözinger, U., Guajardo, P., Guieu, S., Habibi, M., Haguenauer, P., Hans, O., Haubois, X., Haug, M., Haußmann, F., Henning, T., Hippler, S., Hönig, S. F., Horrobin, M., Huber, A., Hubert, Z., Hubin, N., Hummel, C. A., Jakob, G., Janssen, A., Jimenez Rosales, A., Jochum, L., Jocou, L., Kammerer, J., Karl, M., Kaufer, A., Kellner, S., Kendrew, S., Kern, L., Kervella, P., Kiekebusch, M., Kishimoto, M., Klarmann, L., Klein, R., Köhler, R., Kok, Y., Kolb, J., Koutoulaki, M., Kulas, M., Labadie, L., Lacour, S., Lagrange, A.-M., Lapeyrère, V., Laun, W., Lazareff, B., Le Bouquin, J.-B., Léna, P., Lenzen, R., Lévêque, S., Lin, C.-C., Lippa, M., Lutz, D., Magnard, Y., Maire, A.-L., Mehrgan, L., Mérand, A., Millour, F., Mollière, P., Moulin, T., Müller, A., Müller, E., Müller, F., Netzer, H., Neumann, U., Nowak, M., Oberti, S., Ott, T., Pallanca, L., Panduro, J., Pasquini, L., Paumard, T., Percheron, I., Perraut, K., Perrin, G., Peterson, B. M., Petrucci, P.-O., Pflüger, A., Pfuhl, O., Phan Duc, T., Pineda, J. E., Plewa, P. m., Popovic, D., Pott, J.-U., Prieto, A., Pueyo, L., Rabien, S., Ramírez, A., Ramos, J. R., Rau, C., Ray, T., Riquelme, M., Rodríguez-Coira, G., Rohloff, R.-R., Rouan, D., Rousset, G., Sanchez-Bermudez, J., Schartmann, M., Scheithauer, S., Schöller, M., Schuhler, N., Segura-Cox, D., Shangguan, J., Shimizu, T. T., Spyromilio, J., Sternberg, A., Stock, M. R., Straub, O., Straubmeier, C., Sturm, E., Suárez Valles, M., Tacconi, L. J., Thi, W.-F., Tristram, K. R. W., Valenzuela, J. J., Van Boekel, R., Van Dishoeck, E. F., Vermot, P., Vincent, F., Von fellenberg, S., Waisberg, I., Wang, J. J., Wank, I., Weber, J., Weigelt, G., Widmann, F., Wieprecht, E., Wiest, M., Wiezorrek, E., Wittkowski, M., Woillez, J., Wolff, B., Yang, P., Yazici, S., Ziegler, D., Zins, G., and European Southern Observatory (ESO)
Subjects: [SDU]Sciences of the Universe [physics], Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: More than 4000 exoplanets are known to date in systems that differ greatly from our Solar System. In particular, inner exoplanets tend to follow orbits around their parent star that are much more compact than that of Earth. These systems are also extremely diverse, covering a range of intrinsic properties. Studying the main physi- cal processes at play in the innermost regions of the protoplanetary discs is crucial to understanding how these planets form and migrate so close to their host. With GRAVITY, we focused on the study of near-infrared emission of a sample of young intermediate- mass stars, the Herbig Ae/Be stars., Published in The Messenger vol. 178, pp. 38-40, December 2019.
Published: 2019
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23. The GRAVITY young stellar object survey

Author: GRAVITY Collaboration, Eupen, F., Labadie, L., Grellmann, R., Perraut, K., Brandner, W., Duch��ne, G., K��hler, R., Sanchez-Bermudez, J., Lopez, R. Garcia, Garatti, A. Caratti o, Benisty, M., Dougados, C., Garcia, P., Klarmann, L., Amorim, A., Baub��ck, M., Berger, J. P., Caselli, P., Cl��net, Y., Foresto, V. Coud�� du, de Zeeuw, P. T., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Filho, M., Ganci, V., Gao, F., Gendron, E., Genzel, R., Gillessen, S., Heissel, G., Henning, Th., Hippler, S., Horrobin, M., Hubert, Z., Jim��nez-Rosales, A., Jocou, L., Kervella, P., Lacour, S., Lapeyr��re, V., Bouquin, J. B. Le, L��na, P., Ott, T., Paumard, T., Perrin, G., Pfuhl, O., Rodr��guez-Coira, G., Rousset, G., Scheithauer, S., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., van Dishoeck, E., Vincent, F., von Fellenberg, S. D., Widmann, F., Woillez, J., and Wojtczak, A.
Subjects: Techniques: Interferometric, Young stellar object, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, 010309 optics, Stars: Pre-Main Sequence, 0103 physical sciences, Binary star, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Techniques: High Angular Resolution, Orbital elements, Physics, Infrared excess, Herbig Ae/Be, Astronomy and Astrophysics, Mass ratio, Accretion (astrophysics), Binaries: Close, T Tauri star, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Stars: Variables: T Tauri, Astrophysics::Earth and Planetary Astrophysics, Circumbinary planet, Stars: Individual: WW Cha
Abstract: The young T Tauri star WW Cha was recently proposed to be a close binary object with strong infrared and submillimeter excess associated with circum-system emission. This makes WW Cha a very interesting source for studying the influence of dynamical effects on circumstellar as well as circumbinary material. We derive the relative astrometric positions and flux ratios of the stellar companion in WW Cha from the interferometric model fitting of observations made with the VLTI instruments AMBER, PIONIER, and GRAVITY in the near-infrared from 2011 to 2020. For two epochs, the resulting uv-coverage in spatial frequencies permits us to perform the first image reconstruction of the system in the K band. The positions of nine epochs are used to determine the orbital elements and the total mass of the system. We find the secondary star orbiting the primary with a period of T=206.55 days, a semimajor axis of a=1.01 au, and a relatively high eccentricity of e=0.45. Combining the orbital solution with distance measurements from Gaia DR2 and the analysis of evolutionary tracks, the dynamical mass of Mtot=3.20 Msol can be explained by a mass ratio between ~0.5 and 1. The orbital angular momentum vector is in close alignment with the angular momentum vector of the outer disk as measured by ALMA and SPHERE. The analysis of the relative photometry suggests the presence of infrared excess surviving in the system and likely originating from truncated circumstellar disks. The flux ratio between the two components appears variable, in particular in the K band, and may hint at periods of triggered higher and lower accretion or changes in the disks' structures. The knowledge of the orbital parameters, combined with a relatively short period, makes WW Cha an ideal target for studying the interaction of a close young T Tauri binary with its surrounding material, such as time-dependent accretion phenomena., Comment: Accepted for publication in A&A; 24 pages, 14 figures, 3 tables; affiliations corrected
Published: 2021
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24. Modeling the orbital motion of Sgr A*’s near-infrared flares

Author: The GRAVITY Collaboration, Baub��ck, M., Dexter, J., Abuter, R., Amorim, A., Berger, J. P., Bonnet, H., Brandner, W., Cl��net, Y., Foresto, V. Coud�� du, de Zeeuw, P. T., Duvert, G., Eckart, A., Eisenhauer, F., Schreiber, N. M. F��rster, Gao, F., Garcia, P., Gendron, E., Genzel, R., Gerhard, O., Gillessen, S., Habibi, M., Haubois, X., Henning, T., Hippler, S., Horrobin, M., Jim��nez-Rosales, A., Jocou, L., Kervella, P., Lacour, S., Lapeyr��re, V., Bouquin, J. -B. Le, L��na, P., Ott, T., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Rabien, S., Coira, G. Rodriguez, Rousset, G., Scheithauer, S., Stadler, J., Sternberg, A., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., Vincent, F., von Fellenberg, S., Waisberg, I., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), GRAVITY, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Observatoire des Sciences de l'Univers de Grenoble (OSUG), and Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Infrared, Event horizon, Astrophysics::High Energy Astrophysical Phenomena, black hole physics, FOS: Physical sciences, Astrophysics, 01 natural sciences, law.invention, Gravitation, General Relativity and Quantum Cosmology, accretion, law, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 14. Life underwater, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Galaxy: center, 010308 nuclear & particles physics, accretion disks, Galactic Center, Astronomy and Astrophysics, Light curve, Accretion (astrophysics), [SDU]Sciences of the Universe [physics], Space and Planetary Science, Orbital motion, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Flare
Abstract: Infrared observations of Sgr A* probe the region close to the event horizon of the black hole at the Galactic center. These observations can constrain the properties of low-luminosity accretion as well as that of the black hole itself. The GRAVITY instrument at the ESO VLTI has recently detected continuous circular relativistic motion during infrared flares which has been interpreted as orbital motion near the event horizon. Here we analyze the astrometric data from these flares, taking into account the effects of out-of-plane motion and orbital shear of material near the event horizon of the black hole. We have developed a new code to predict astrometric motion and flux variability from compact emission regions following particle orbits. Our code combines semi-analytic calculations of timelike geodesics that allow for out-of-plane or elliptical motions with ray tracing of photon trajectories to compute time-dependent images and light curves. We apply our code to the three flares observed with GRAVITY in 2018. We show that all flares are consistent with a hotspot orbiting at R$\sim$9 gravitational radii with an inclination of $i\sim140^\circ$. The emitting region must be compact and less than $\sim5$ gravitational radii in diameter. We place a further limit on the out-of-plane motion during the flare., Comment: Accepted in A&A
Published: 2020
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25. GRAVITY chromatic imaging of η Car’s core: Milliarcsecond resolution imaging of the wind-wind collision zone (Brγ, He I)

Author: Sanchez-Bermudez, J., Weigelt, G., Bestenlehner, J.M., Kervella, P., Brandner, W., Henning, T., Mueller, A., Perrin, G., Pott, J.-U., Schoeller, M., van Boeke, R., Abuter, R., Accardo, M., Amorim, A., Anugu, N., Avila, G., Benisty, M., Berger, J.P., Blind, N., Bonnet, H., Bourget, P., Brast, R., Buron, A., Cantalloube, F., Garatti, A.C.O., Cassaing, F., Chapron, F., Choquet, E., Clenet, Y., Collin, C., du Foresto, V.C., de Wit, W., de Zeeuw, T., Deen, C., Delplancke-Stroebele, F., Dembet, R., Derie, F., Dexter, J., Duvert, G., Ebert, M., Eckart, A., Eisenhauer, F., Esselborn, M., Fedou, P., Garcia, P.J.V., Dabo, C.E.G., Lopez, R.G., Gao, F., Gendron, E., Genzel, R., Gillessen, S., Haubois, X., Haug, M., Haussmann, F., Hippler, S., Horrobin, M., Huber, A., Hubert, Z., Hubin, N., Hummel, C.A., Jakob, G., Jochum, L., Jocou, L., Karl, M., Kaufer, A., Kellner, S., Kendrew, S., Kern, L., Kiekebusch, M., Klein, R., Kolb, J., Kulas, M., Lacour, S., Lapeyrere, V., Lazareff, B., Le Bouquin, J.-B., Lena, P., Lenzen, R., Leveque, S., Lippa, M., Magnard, Y., Mehrgan, L., Mellein, M., Merand, A., Moreno-Ventas, J., Moulin, T., Mueller, E., Mueller, F., Neumann, U., Oberti, S., Ott, T., Pallanca, L., Panduro, J., Pasquini, L., Paumard, T., Percheron, I., Perraut, K., Petrucci, P.-O., Pflueger, A., Pfuhl, O., Duc, T.P., Plewa, P.M., Popovic, D., Rabien, S., Ramirez, A., Ramos, J., Rau, C., Riquelme, M., Rodriguez-Coira, G., Rohloff, R.-R., Rosales, A., Rousset, G., Scheithauer, S., Schuhler, N., Spyromilio, J., Straub, O., Straubmeier, C., Sturm, E., Suarez, M., Tristram, K.R.W., Ventura, N., Vincent, F., Waisberg, I., Wank, I., Widmann, F., Wieprecht, E., Wiest, M., Wiezorrek, E., Wittkowski, M., Woillez, J., Wolff, B., Yazici, S., Ziegler, D., Zins, G., and Collaboration, GRAVITY
Subjects: Astrophysics::Solar and Stellar Astrophysics
Abstract: Context. η Car is one of the most intriguing luminous blue variables in the Galaxy. Observations and models of the X-ray, ultraviolet, optical, and infrared emission suggest a central binary in a highly eccentric orbit with a 5.54 yr period residing in its core. 2D and 3D radiative transfer and hydrodynamic simulations predict a primary with a dense and slow stellar wind that interacts with the faster and lower density wind of the secondary. The wind-wind collision scenario suggests that the secondary’s wind penetrates the primary’s wind creating a low-density cavity in it, with dense walls where the two winds interact. However, the morphology of the cavity and its physical properties are not yet fully constrained.\ud \ud Aims. We aim to trace the inner ∼5–50 au structure of η Car’s wind-wind interaction, as seen through Brγ and, for the first time, through the He I 2s-2p line.\ud \ud Methods. We have used spectro-interferometric observations with the K-band beam-combiner GRAVITY at the VLTI. The analyses of the data include (i) parametrical model-fitting to the interferometric observables, (ii) a CMFGEN model of the source’s spectrum, and (iii) interferometric image reconstruction.\ud \ud Results. Our geometrical modeling of the continuum data allows us to estimate its FWHM angular size close to 2 mas and an elongation ratio ϵ = 1.06 ± 0.05 over a PA = 130° ± 20°. Our CMFGEN modeling of the spectrum helped us to confirm that the role of the secondary should be taken into account to properly reproduce the observed Brγ and He I lines. Chromatic images across the Brγ line reveal a southeast arc-like feature, possibly associated to the hot post-shocked winds flowing along the cavity wall. The images of the He I 2s-2p line served to constrain the 20 mas (∼50 au) structure of the line-emitting region. The observed morphology of He I suggests that the secondary is responsible for the ionized material that produces the line profile. Both the Brγ and the He I 2s-2p maps are consistent with previous hydrodynamical models of the colliding wind scenario. Future dedicated simulations together with an extensive interferometric campaign are necessary to refine our constraints on the wind and stellar parameters of the binary, which finally will help us predict the evolutionary path of η Car.
Published: 2018

26. Resolving faint structures in the debris disk around TWA 7

Author: Olofsson, J., van Holstein, R. G., Boccaletti, A., Janson, M., Thebault, P., Gratton, R., Lazzoni, C., Kral, Q., Bayo, A., Canovas, H., Caceres, C., Ginski, C., Pinte, C., Asensio-Torres, R., Chauvin, G., Desidera, S., Henning, Th., Langlois, M., Milli, J., Schlieder, J. E., Schreiber, M. R., Augereau, J.-C., Bonnefoy, M., Buenzli, E., Brandner, W., Durkan, S., Engler, N., Feldt, M., Godoy, N., Grady, C., Hagelberg, J., Lagrange, A.-M., Lannier, J., Ligi, R., Maire, A.-L., Mawet, D., Ménard, F., Mesa, D., Mouillet, D., Peretti, S., Perrot, C., Salter, G., Schmidt, T., Sissa, E., Thalmann, C., Vigan, Arthur, Abe, L., Feautrier, P., Le Mignant, D., Moulin, T., PAVLOV, A., Rabou, P., Rousset, G., Roux, A., Schreiber, R., Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Stockholm University, INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), European Southern Observatory (ESO), Caltech Department of Astronomy [Pasadena], California Institute of Technology (CALTECH), Geneva Observatory, University of Geneva [Switzerland], Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich), Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Copernicus Astronomical Center of the Polish Academy of Sciences (CAMK), Polish Academy of Sciences (PAN), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Universiteit Leiden, Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Université de Genève = University of Geneva (UNIGE), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), ANR-16-CE31-0013,PLANET-FORMING-DISKS,De meilleurs modèles pour de meilleures données(2016), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Earth and Planetary Astrophysics (astro-ph.EP), Astrophysics - Solar and Stellar Astrophysics, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], instrumentation: high angular resolution, FOS: Physical sciences, Astrophysics::Solar and Stellar Astrophysics, instrumentation: polarimeters, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, circumstellar matter, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract: Debris disks are the intrinsic by-products of the star and planet formation processes. Most likely due to instrumental limitations and their natural faintness, little is known about debris disks around low-mass stars, especially when it comes to spatially resolved observations. We present new VLT/SPHERE IRDIS Dual-Polarization Imaging (DPI) observations in which we detect the dust ring around the M2 spectral type star TWA\,7. Combined with additional Angular Differential Imaging observations we aim at a fine characterization of the debris disk and setting constraints on the presence of low-mass planets. We model the SPHERE DPI observations and constrain the location of the small dust grains, as well as the spectral energy distribution of the debris disk, using the results inferred from the observations, and perform simple N-body simulations. We find that the dust density distribution peaks at 25 au, with a very shallow outer power-law slope, and that the disk has an inclination of 13 degrees with a position angle of 90 degrees East of North. We also report low signal-to-noise detections of an outer belt at a distance of ~52 au from the star, of a spiral arm in the Southern side of the star, and of a possible dusty clump at 3.9 au. These findings seem to persist over timescales of at least a year. Using the intensity images, we do not detect any planets in the close vicinity of the star, but the sensitivity reaches Jovian planet mass upper limits. We find that the SED is best reproduced with an inner disk at 7 au and another belt at 25 au. We report the detections of several unexpected features in the disk around TWA\,7. A yet undetected 100 M$_\oplus$ planet with a semi-major axis at 20-30 au could possibly explain the outer belt as well as the spiral arm. We conclude that stellar winds are unlikely to be responsible for the spiral arm., Comment: Accepted by A&A, 17 pages
Published: 2018
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27. Investigating the young solar system analog HD 95086

Author: Chauvin, G., Gratton, R., Bonnefoy, M., Lagrange, A. -M, Boer, J., Arthur Vigan, Beust, H., Lazzoni, C., Boccaletti, A., Galicher, R., Desidera, S., Delorme, P., Keppler, M., Lannier, J., Maire, A. -L, Mesa, D., Meunier, N., Kral, Q., Henning, T., Menard, F., Moor, A., Avenhaus, H., Bazzon, A., Janson, M., Beuzit, J. -L, Bhowmik, T., Bonavita, M., Borgniet, S., Brandner, W., Cheetham, A., Cudel, M., Feldt, M., Fontanive, C., Ginski, C., Hagelberg, J., Janin-Potiron, P., Lagadec, E., Langlois, M., Le Coroller, H., Messina, S., Meyer, M., Mouillet, D., Peretti, S., Perrot, C., Rodet, L., Samland, M., Sissa, E., Olofsson, J., Salter, G., Schmidt, T., Zurlo, A., Milli, J., Boekel, R., Quanz, S., Wilson, P. A., Feautrier, P., Le Mignant, D., Perret, D., Ramos, J., Rochat, S., Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, Universidad de Chile (UCHILE), Institute for Astronomy [Zürich], Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich), Department of Astronomy, Stockholm University, Observatoire Astronomique de l'Université de Genève (ObsGE), Université de Genève (UNIGE), Institute for Astronomy [Edinburgh] (IfA), University of Edinburgh, Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Haute-Provence (OHP), Institut Pythéas (OSU PYTHEAS), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut de Recherche pour le Développement (IRD), INAF - Osservatorio Astrofisico di Catania (OACT), Laboratoire d'interaction du rayonnement X avec la matière (LIXAM), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), European Southern Observatory (ESO), Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), Institute of Astronomy [ETH Zürich], Department of Physics [ETH Zürich] (D-PHYS), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich)-Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Universidad de Chile = University of Chile [Santiago] (UCHILE), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Centre National de la Recherche Scientifique (CNRS), Universiteit Leiden, Université de Genève = University of Geneva (UNIGE), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), and We acknowledge financial support from the Programme National de Planétologie (PNP) and the Programme National de Physique Stellaire (PNPS) of CNRS-INSU. This work has also been supported by a grant from the French Labex OSUG@2020 (Investissements d’avenir – ANR10 LABX56). The project is supported by CNRS, by the Agence Nationale de la Recherche (ANR-14-CE33-0018).A (Germany), INAF (Italy), FINES (Switzerland) and NOVA (Netherlands). SPHERE also received funding from the European Commission Sixth and Seventh Framework Programmes as part of the Optical Infrared Coordination Network for Astronomy (OPTICON) under grant number RII3-Ct-2004-001566 for FP6 (2004–2008), grant number 226604 for FP7 (2009–2012) and grant number 312430 for FP7 (2013–2016).
Subjects: Earth and Planetary Astrophysics (astro-ph.EP), [PHYS]Physics [physics], Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics::Galaxy Astrophysics, ComputingMilieux_MISCELLANEOUS, Astrophysics - Earth and Planetary Astrophysics
Abstract: HD95086 (A8V, 17Myr) hosts a rare planetary system for which a multi-belt debris disk and a giant planet of 4-5MJup have been directly imaged. Our study aims to characterize the physical and orbital properties of HD95086b, search for additional planets at short and wide orbits and image the cold outer debris belt in scattered light. We used HARPS at the ESO 3.6m telescope to monitor the radial velocity of HD95086 over 2 years and investigate the existence of giant planets at less than 3au orbital distance. With the IRDIS dual-band imager and the IFS integral field spectrograph of SPHERE at VLT, we imaged the faint circumstellar environment beyond 10au at six epochs between 2015 and 2017. We do not detect additional giant planets around HD95086. We identified the nature (bound companion or background contaminant) of all point-like sources detected in the IRDIS field of view. None of them correspond to the ones recently discovered near the edge of the cold outer belt by ALMA. HD95086b is resolved for the first time in J-band with IFS. Its near-infrared spectral energy distribution is well fitted by a few dusty and/or young L7-L9 dwarf spectral templates. The extremely red 1-4um spectral distribution is typical of low-gravity objects at the L/T spectral type transition. The planet's orbital motion is resolved between January 2015 and May 2017. Together with past NaCo measurements properly re-calibrated, our orbital fitting solutions favor a retrograde low to moderate-eccentricity orbit e=0.2 (0.0 to 0.5), with a semi-major axis 52au corresponding to orbital periods of 288$ yrs and an inclination that peaks at i = 141deg, which is compatible with a planet-disk coplanar configuration. Finally, we report the detection in polarimetric differential imaging of the cold outer debris belt between 100 and 300au, consistent in radial extent with recent ALMA 1.3mm resolved observations., Comment: 23 pages, 19 figures, accepted in A&A (Dec 28th, 2017)
Published: 2018
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28. GRAVITY chromatic imaging of η Car's core. Milliarcsecond resolution imaging of the wind-wind collision zone (Brγ, He I)

Author: Collaboration, G., Sanchez-Bermudez, J., Weigelt, G., Bestenlehner, J., Kervella, P., Brandner, W., Henning, T., Müller, A., Perrin, G., Pott, J., Schöller, M., van Boekel, R., Abuter, R., Accardo, M., Amorim, A., Anugu, N., Ávila, G., Benisty, M., Berger, J., Blind, N., Bonnet, H., Bourget, P., Brast, R., Buron, A., Cantalloube, F., Caratti O Garatti, A., Cassaing, F., Chapron, F., Choquet, E., Clénet, Y., Collin, C., Coudé Du Foresto, V., de Wit, W., de Zeeuw, T., Deen, C., Delplancke-Ströbele, F., Dembet, R., Derie, F., Dexter, J., Duvert, G., Ebert, M., Eckart, A., Eisenhauer, F., Esselborn, M., Fédou, P., Garcia, P., Garcia Dabo, C., Garcia Lopez, R., Gao, F., Gendron, E., Genzel, R., Gillessen, S., Haubois, X., Haug, M., Haussmann, F., Hippler, S., Horrobin, M., Huber, A., Hubert, Z., Hubin, N., Hummel, C., Jakob, G., Jochum, L., Jocou, L., Karl, M., Kaufer, A., Kellner, S., Kendrew, S., Kern, L., Kiekebusch, M., Klein, R., Kolb, J., Kulas, M., Lacour, S., Lapeyrère, V., Lazareff, B., Le Bouquin, J., Léna, P., Lenzen, R., Lévêque, S., Lippa, M., Magnard, Y., Mehrgan, L., Mellein, M., Mérand, A., Moreno-Ventas, J., Moulin, T., Müller, E., Müller, F., Neumann, U., Oberti, S., Ott, T., Pallanca, L., Panduro, J., Pasquini, L., Paumard, T., Percheron, I., Perraut, K., Petrucci, P., Pflüger, A., Pfuhl, O., Duc, T., Plewa, P., Popovic, D., Rabien, S., Ramirez, A., Ramos, J., Rau, C., Riquelme, M., Rodríguez-Coira, G., Rohloff, R., Rosales, A., Rousset, G., Scheithauer, S., Schuhler, N., Spyromilio, J., Straub, O., Straubmeier, C., Sturm, E., Suarez, M., Tristram, K., Ventura, N., Vincent, F., Waisberg, I., Wank, I., Widmann, F., Wieprecht, E., Wiest, M., Wiezorrek, E., Wittkowski, M., Woillez, J., Wolff, B., Yazici, S., Ziegler, D., and Zins, G.
Subjects: Astrophysics::Solar and Stellar Astrophysics
Abstract: Context. η Car is one of the most intriguing luminous blue variables in the Galaxy. Observations and models of the X-ray, ultraviolet, optical, and infrared emission suggest a central binary in a highly eccentric orbit with a 5.54 yr period residing in its core. 2D and 3D radiative transfer and hydrodynamic simulations predict a primary with a dense and slow stellar wind that interacts with the faster and lower density wind of the secondary. The wind-wind collision scenario suggests that the secondary's wind penetrates the primary's wind creating a low-density cavity in it, with dense walls where the two winds interact. However, the morphology of the cavity and its physical properties are not yet fully constrained. Aims: We aim to trace the inner ̃5-50 au structure of η Car's wind-wind interaction, as seen through Brγ and, for the first time, through the He I 2s-2p line. Methods: We have used spectro-interferometric observations with the K-band beam-combiner GRAVITY at the VLTI. The analyses of the data include (i) parametrical model-fitting to the interferometric observables, (ii) a CMFGEN model of the source's spectrum, and (iii) interferometric image reconstruction. Results: Our geometrical modeling of the continuum data allows us to estimate its FWHM angular size close to 2 mas and an elongation ratio ∊ = 1.06 ± 0.05 over a PA = 130° ± 20°. Our CMFGEN modeling of the spectrum helped us to confirm that the role of the secondary should be taken into account to properly reproduce the observed Brγ and He I lines. Chromatic images across the Brγ line reveal a southeast arc-like feature, possibly associated to the hot post-shocked winds flowing along the cavity wall. The images of the He I 2s-2p line served to constrain the 20 mas (̃50 au) structure of the line-emitting region. The observed morphology of He I suggests that the secondary is responsible for the ionized material that produces the line profile. Both the Brγ and the He I 2s-2p maps are consistent with previous hydrodynamical models of the colliding wind scenario. Future dedicated simulations together with an extensive interferometric campaign are necessary to refine our constraints on the wind and stellar parameters of the binary, which finally will help us predict the evolutionary path of η Car.
Published: 2018

29. GRAVITY chromatic imaging of Eta Car's core

Author: GRAVITY Collaboration, Sanchez-Bermudez, J., Weigelt, G., Bestenlehner, J. M., Kervella, P., Brandner, W., Henning, Th., Müller, A., Perrin, G., Pott, J. -U., Schöller, M., van Boekel, R., Abuter, R., Accardo, M., Amorim, A., Anugu, N., Ávila, G., Benisty, M., Berger, J. P., Blind, N., Bonnet, H., Bourget, P., Brast, R., Buron, A., Cantalloube, F., Garatti, A. Caratti o, Cassaing, F., Chapron, F., Choquet, E., Clénet, Y., Collin, C., Foresto, V. Coudé du, de Wit, W., de Zeeuw, T., Deen, C., Delplancke-Ströbele, F., Dembet, R., Derie, F., Dexter, J., Duvert, G., Ebert, M., Eckart, A., Eisenhauer, F., Esselborn, M., Fédou, P., Garcia, P. J. V., Dabo, C. E. Garcia, Lopez, R. Garcia, Gao, F., Gendron, E., Genzel, R., Gillessen, S., Haubois, X., Haug, M., Haussmann, F., Hippler, S., Horrobin, M., Huber, A., Hubert, Z., Hubin, N., Hummel, C. A., Jakob, G., Jochum, L., Jocou, L., Karl, M., Kaufer, A., Kellner, S., Kendrew, S., Kern, L., Kiekebusch, M., Klein, R., Kolb, J., Kulas, M., Lacour, S., Lapeyrère, V., Lazareff, B., Bouquin, J. -B. Le, Léna, P., Lenzen, R., Levêque, S., Lippa, M., Magnard, Y., Mehrgan, L., Mellein, M., Mérand, A., Moreno-Ventas, J., Moulin, T., Müller, E., Müller, F., Neumann, U., Oberti, S., Ott, T., Pallanca, L., Panduro, J., Pasquini, L., Paumard, T., Percheron, I., Perraut, K., Petrucci, P. -O., Pflüger, A., Pfuhl, O., Duc, T. P., Plewa, P. M., Popovic, D., Rabien, S., Ramirez, A., Ramos, J., Rau, C., Riquelme, M., Rodríguez-Coira, G., Rohloff, R. -R., Rosales, A., Rousset, G., Scheithauer, S., Schuhler, N., Spyromilio, J., Straub, O., Straubmeier, C., Sturm, E., Suarez, M., Tristram, K. R. W., Ventura, N., Vincent, F., Waisberg, I., Wank, I., Widmann, F., Wieprecht, E., Wiest, M., Wiezorrek, E., Wittkowski, M., Woillez, J., Wolff, B., Yazici, S., Ziegler, D., Zins, G., European Southern Observatory (ESO), Max-Planck-Institut für Radioastronomie (MPIFR), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, Institut de biologie et chimie des protéines [Lyon] (IBCP), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), CENTRA-SIM, IDL-Faculdade de Ciencias da Universidade de Lisboa, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Max Planck Institute for Astronomy (MPIA), DOTA, ONERA, Université Paris Saclay [Châtillon], ONERA-Université Paris-Saclay, Caltech Department of Astronomy [Pasadena], California Institute of Technology (CALTECH), Max Planck Institute for Extraterrestrial Physics (MPE), Observatoire de Paris - Site de Paris (OP), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), Galaxies, Etoiles, Physique, Instrumentation (GEPI), PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Norwegian Institute for Air Research (NILU), European Southern Observatory [Santiago] (ESO), Department of General, Centre de recherche sur l'eau, Veolia Environnement, University of Bologna [Italy], School of Electrical Engineering (ETF), University of Belgrade [Belgrade], Universidad Mayor, Diamond Light Source, Harwell, Berks, England, Délégation à la Recherche Clinique et à l'Innovation (DRCI), Universität zu Köln, Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174) (FEMTO-ST), Université de Franche-Comté (UFC)-Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Technologie de Belfort-Montbeliard (UTBM), AUTRES, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), DOTA, ONERA, Université Paris Saclay (COmUE) [Châtillon], ONERA-Université Paris Saclay (COmUE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Franche-Comté (UFC), and Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [PHYS]Physics [physics], Astrophysics - Solar and Stellar Astrophysics, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], ComputingMilieux_MISCELLANEOUS, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract: Eta Car is one of the most intriguing luminous blue variables in the Galaxy. Observations and models at different wavelengths suggest a central binary with a 5.54 yr period residing in its core. 2D and 3D radiative transfer and hydrodynamic simulations predict a primary with a dense and slow stellar wind that interacts with the faster and lower density wind of the secondary. The wind-wind collision scenario suggests that the secondary's wind penetrates the primary's wind creating a low-density cavity in it, with dense walls where the two winds interact. We aim to trace the inner ~5-50 au structure of Eta Car's wind-wind interaction, as seen through BrG and, for the first time, through the He I 2s-2p line. We have used spectro-interferometric observations with GRAVITY at the VLTI. Our modeling of the continuum allows us to estimate its FWHM angular size close to 2 mas and an elongation ratio of 1.06 +/- 0.05 over a PA = 130 +/- 20 deg. Our CMFGEN modeling helped us to confirm that the role of the secondary should be taken into account to properly reproduce the observed BrG and He I lines. Chromatic images across BrG reveal a southeast arc-like feature, possibly associated to the hot post-shocked winds flowing along the cavity wall. The images of He I 2s-2p served to constrain the 20 mas structure of the line-emitting region. The observed morphology of He I suggests that the secondary is responsible for the ionized material that produces the line profile. Both the BrG and the He I 2s-2p maps are consistent with previous hydrodynamical models of the colliding wind scenario. Future dedicated simulations together with an extensive interferometric campaign are necessary to refine our constraints on the wind and stellar parameters of the binary, which finally will help us predict the evolutionary path of Eta Car., Comment: 32 pages, 27 figures (14 in the main body, 13 in the appendices), accepted for publication in AA
Published: 2018
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30. GRAVITY Spectro-interferometric Study of the Massive Multiple Stellar System HD 93206 A

Author: Sanchez-Bermudez, J., Alberdi, A., Barba, R., Bestenlehner, J.M., Cantalloube, F., Brandner, W., Henning, T., Hummel, C.A., Maiz Apellaniz, J., Pott, J.-U., Schodel, R., and van Boekel, R.
Subjects: Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: Characterization of the dynamics of massive star systems and the astrophysical properties of the interacting components are a prerequisite for understanding their formation and evolution. Optical interferometry at milliarcsecond resolution is a key observing technique for resolving high-mass multiple compact systems. Here, we report on Very Large Telescope Interferometer/GRAVITY, Magellan/Folded-port InfraRed Echellette, and MPG2.2 m/FEROS observations of the late-O/early-B type system HD 93206 A, which is a member of the massive cluster Collinder 228 in the Carina nebula complex. With a total mass of about $90\,{M}_{\odot }$, it is one of the most compact massive quadruple systems known. In addition to measuring the separation and position angle of the outer binary Aa–Ac, we observe Brγ and He i variability in phase with the orbital motion of the two inner binaries. From the differential phase (${{\rm{\Delta }}}_{\phi }$) analysis, we conclude that the Brγ emission arises from the interaction regions within the components of the individual binaries, which is consistent with previous models for the X-ray emission of the system based on wind–wind interaction. With an average 3σ deviation of ${{\rm{\Delta }}}_{\phi }\sim 15^\circ $, we establish an upper limit of p ~ 0.157 mas (0.35 au) for the size of the Brγ line-emitting region. Future interferometric observations with GRAVITY using the 8 m Unit Telescopes will allow us to constrain the line-emitting regions down to angular sizes of 20 μas (0.05 au at the distance of the Carina nebula).
Published: 2017

31. The COSMIC-DANCE project: Unravelling the origin of the mass function

Author: Hervé Bouy, Bertin, E., Sarro, L. M., Barrado, D., Berihuete, A., Olivares, J., Moraux, E., Bouvier, J., Tamura, M., Cuillandre, J. -C, Beletsky, Y., Wright, N., Huelamo, N., Allen, L., Solano, E., Brandner, W., M2A 2017, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut d'Astrophysique de Paris (IAP), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Riken, RIKEN - Institute of Physical and Chemical Research [Japon] (RIKEN), Canada-France-Hawaii Telescope Corporation (CFHT), National Research Council of Canada (NRC)-Centre National de la Recherche Scientifique (CNRS)-University of Hawai'i [Honolulu] (UH), Newcastle University [Newcastle], Spanish Virtual Observatory - Observatorio Virtual Español (SVO), Spanish Virtual Observatory - Observatorio Virtual Español, Departamento de Astrofisica [Madrid], Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Pomies, Marie-Paule, and Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.ASTR.IM] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM]
Abstract: International audience; The COSMIC-DANCE project is an observational program aiming at understanding the origin and evolution of ultracool objects by measuring the mass function and internal dynamics of young nearby associations down to the fragmentation limit. The least massive members of young nearby associations are identified using modern statistical methods in a multi-dimensional space made of optical and infrared luminosities and colors and proper motions. The photometry and astrometry are obtained by combining ground and in some case space based archival observations with new observations, covering between one and two decades.
Published: 2016

32. GRAVITY: the VLTI 4-beam combiner for narrow-angle astrometry and interferometric imaging

Author: Blind, N., Eisenhauer, F., Gillessen, S., Kok, Y., Lippa, M., Perrin, G., Dembet, R., Fedou, P., Lacour, S., Perraut, K., Jocou, L., Burtscher, L., Hans, O., Haug, M., Haussmann, F., Huber, S., Janssen, A., Kellner, S., Ott, T., Pfuhl, O., Sturm, E., Weber, J., Wieprecht, E., Amorim, A., Brandner, W., and Straubmeier, C.
Subjects: Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics
Abstract: GRAVITY is the second generation Very Large Telescope Interferometer instrument for precision narrow-angle astrometry and interferometric imaging in the Near Infra-Red (NIR). It shall provide precision astrometry of order 10 microarcseconds, and imaging capability at a few milliarcsecond resolution, and hence will revolutionise dynamical measurements of celestial objects. GRAVITY is currently in the last stages of its integration and tests in Garching at MPE, and will be delivered to the VLT Interferometer (VLTI) in 2015. We present here the instrument, with a particular focus on the components making use of fibres: integrated optics beam combiners, polarisation rotators, fibre differential delay lines, and the metrology., 8 pages, 3 figures. Proceeding of the conference "Fiber optics in astronomy IV". The follwoing authors made significant contribution regarding the work on fibers reported in this paper (ordered by institute and alphabetical order): IPAG: L. Jocou, K. Perraut; LESIA: R. Dembet, P. Fedou, S. Lacour, G. Perrin; MPE: N. Blind, F. Eisenhauer, S. Gillessen,, Y. Kok, M. Lippa
Published: 2015

33. Age spread in W3 Main: LBT/LUCI near-infrared spectroscopy of the massive stellar content

Author: Bik, A., Henning, Th., Stolte, A., Brandner, W., Gouliermis, D. A., Gennaro, M., Pasquali, A., Rochau, B., Beuther, H., Ageorges, N., Seifert, W., Wang, Y., and Kudryavtseva, N.
Subjects: Astrophysics of Galaxies (astro-ph.GA), FOS: Physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Astrophysics of Galaxies, Astrophysics::Galaxy Astrophysics
Abstract: We present near-infrared multi-object spectroscopy and JHKs imaging of the massive stellar content of the Galactic star-forming region W3 Main, obtained with LUCI at the Large Binocular Telescope. We confirm 15 OB stars in W3 Main and derive spectral types between O5V and B4V from their absorption line spectra. Three massive Young Stellar Objects are identified by their emission line spectra and near-infrared excess. The color-color diagram of the detected sources allows a detailed investigation of the slope of the near-infrared extinction law towards W3 Main. Analysis of the Hertzsprung Russell diagram suggests that the Nishiyama extinction law fits the stellar population of W3 Main best (E(J-H)/E(H-Ks) = 1.76 and R_(Ks) = 1.44). From our spectrophotometric analysis of the massive stars and the nature of their surrounding HII regions we derive the evolutionary sequence of W3 Main and we find evidence of an age spread of at least 2-3 Myr. While the most massive star (IRS2) is already evolved, indications for high-mass pre-main-sequence evolution is found for another star (IRS N1), deeply embedded in an ultra compact HII region, in line with the different evolutionary phases observed in the corresponding HII regions. We derive a stellar mass of W3 Main of (4 +- 1) 10^3 Msun, by extrapolating from the number of OB stars using a Kroupa IMF and correcting for our spectroscopic incompleteness. We have detected the photospheres of OB stars from the more evolved diffuse HII region to the much younger UCHII regions, suggesting that these stars have finished their formation and cleared away their circumstellar disks very fast. Only in the hyper-compact HII region (IRS5), the early type stars seem to be still surrounded by circumstellar material., Accepted by ApJ, 14 pages, 4 figures
Published: 2011

34. The present-day mass function of the Quintuplet cluster

Author: Hu��mann, B., Stolte, A., Brandner, W., and Gennaro, M.
Subjects: Astrophysics of Galaxies (astro-ph.GA), FOS: Physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Astrophysics of Galaxies, Astrophysics::Galaxy Astrophysics
Abstract: Context: The stellar mass function is a probe for a potential dependence of star formation on the environment. Only a few young clusters are known to reside within the Central Molecular Zone and can serve as testbeds for star formation under the extreme conditions in this region. Aims: We determine the present-day mass function of the Quintuplet cluster, a young massive cluster in the vicinity of the Galactic centre. Methods: We use two epochs of high resolution near infrared imaging data obtained with NAOS/CONICA at the ESO VLT to measure the individual proper motions of stars in the Quintuplet cluster in the cluster reference frame. An unbiased sample of cluster members within a radius of 0.5 pc from the cluster centre was established based on their common motion with respect to the field and a subsequent colour-cut. Initial stellar masses were inferred from four isochrones covering ages from 3 to 5 Myr and two sets of stellar evolution models. For each isochrone the present-day mass function of stars was determined for the full sample of main sequence cluster members using an equal number binning scheme. Results: We find the slope of the present-day mass function in the central part of the Quintuplet cluster to be alpha = -1.66+-0.14 for an approximate mass range from 5 to 40M_Sun, which is significantly flatter than the Salpeter slope of alpha = -2.35. The flattening of the present-day mass function may be caused by rapid dynamical evolution of the cluster in the strong Galactic centre tidal field. The derived mass function slope is compared to the values found in other young massive clusters in the Galaxy.
Published: 2011

35. Infrared Narrow-Band Tomography of the Local Starburst NGC 1569 with LBT/LUCIFER

Author: Pasquali, A., Bik, A., Zibetti, S., Ageorges, N., Seifert, W., Brandner, W., Rix, H. -W., Juette, M, Knierim, V., Buschkamp, P., Feiz, C., Gemperlein, H., Germeroth, A., Hoffmann, R., Laun, W., Lederer, R., Lehmitz, M., Lenzen, R., Mall, U., Mandel, H., Mueller, P., Naranjo, V., Polsterer, K., Quirrenbach, A., Schaeffner, L., Storz, C., and Weiser, P.
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO), Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: We used the near-IR imager/spectrograph LUCIFER mounted on the Large Binocular Telescope (LBT) to image, with sub-arcsec seeing, the local dwarf starburst NGC 1569 in the JHK bands and HeI 1.08 micron, [FeII] 1.64 micron and Brgamma narrow-band filters. We obtained high-quality spatial maps of HeI, [FeII] and Brgamma emission across the galaxy, and used them together with HST/ACS images of NGC 1569 in the Halpha filter to derive the two-dimensional spatial map of the dust extinction and surface star formation rate density. We show that dust extinction is rather patchy and, on average, higher in the North-West (NW) portion of the galaxy [E_g(B-V) = 0.71 mag] than in the South-East [E_g(B-V) = 0.57 mag]. Similarly, the surface density of star formation rate peaks in the NW region of NGC 1569, reaching a value of about 4 x 10^-6 M_sun yr^-1 pc^-2. The total star formation rate as estimated from the integrated, dereddened Halpha luminosity is about 0.4 M_sun yr^-1, and the total supernova rate from the integrated, dereddened [FeII] luminosity is about 0.005 yr^-1 (assuming a distance of 3.36 Mpc). The azimuthally averaged [FeII]/Brgamma flux ratio is larger at the edges of the central, gas-deficient cavities (encompassing the super star clusters A and B) and in the galaxy outskirts. If we interpret this line ratio as the ratio between the average past star formation (as traced by supernovae) and on-going activity (represented by OB stars able to ionize the interstellar medium), it would then indicate that star formation has been quenched within the central cavities and lately triggered in a ring around them. The number of ionizing hydrogen and helium photons as computed from the integrated, dereddened Halpha and HeI luminosities suggests that the latest burst of star formation occurred about 4 Myr ago and produced new stars with a total mass of ~1.8 x 10^6 M_sun. [Abridged], Comment: accepted for publication in AJ
Published: 2011
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36. Direct imaging of the young spectroscopic binary HD 160934

Author: Hormuth, F, Janson, Markus, Hippler, Stefan, Brandner, Wolfgang, Hormuth, Felix, Henning, T, Janson, M, Hippler, S, Brandner, W, and Henning, Thomas
Subjects: Diffraction, Physics, Astrophysics (astro-ph), Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Binary number, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Lucky imaging, law.invention, Radial velocity, Photometry (optics), Telescope, Stars, Space and Planetary Science, law, bepress|Physical Sciences and Mathematics|Astrophysics and Astronomy, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics, AB Doradus moving group
Abstract: We report on the direct detection of a close companion to HD 160934, a young active star, SB1 spectroscopic binary, and suggested member of the AB Doradus moving group. High angular resolution at the Calar Alto 2.2m telescope was achieved by means of the Lucky Imaging technique, allowing direct imaging close to the diffraction limit in the SDSS z' band. Our results are combined with pre-discovery HST archive data, own UBVRI broadband photometry, published JHK magnitudes, and available radial velocity measurements to constrain the physical properties of the HD 160934 close binary. We suggest that the direct detection may be identical to the spectroscopically discovered companion., 5 pages, 1 figure, submitted to A&A
Published: 2006

37. Search for Giant Planets around White Dwarfs with HST, Spitzer, and VLT

Author: Friedrich, S., Zinnecker, H., Correia, S., Brandner, W., Burleigh, M., and McCaughrean, M.
Subjects: Astrophysics (astro-ph), FOS: Physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: For the last three years we have performed a survey for young (, 6 pages, 4 figures, 15th European Workshop on White Dwarfs
Published: 2006

38. GRAVITY: The adaptive optics assisted, two object beam combiner for the VLTI

Author: Gillessen, S., Perrin, G., Brandner, W., Straubmeier, C., Eisenhauer, F., Rabien, S., Eckart, A., Lena, P., Genzel, R., Paumard, T., and Hippler, S.
Subjects: General Relativity and Quantum Cosmology, Astrophysics (astro-ph), Astrophysics::Instrumentation and Methods for Astrophysics, Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics::Earth and Planetary Astrophysics, Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: We present the adaptive optics assisted, near-infrared VLTI instrument - GRAVITY - for precision narrow-angle astrometry and interferometric phase referenced imaging of faint objects. Precision astrometry and phase-referenced interferometric imaging will realize the most advanced vision of optical/infrared interferometry with the VLT. Our most ambitious science goal is to study motions within a few times the event horizon size of the Galactic Center massive black hole and to test General Relativity in its strong field limit. We define the science reference cases for GRAVITY and derive the top level requirements for GRAVITY. The installation of the instrument at the VLTI is planned for 2012., Comment: 9 pages, Advances in Stellar Interferometry, SPIE Proc. Vol. 6268, 626811 (2006)
Published: 2006
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39. A NICMOS Direct Imaging Search for Giant Planets around the Single White Dwarfs in the Hyades

Author: Friedrich, S., Zinnecker, H., Brandner, W., Correia, S., and McCaughrean, M.
Subjects: Astrophysics (astro-ph), Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: We report preliminary results from our search for massive giant planets (6-12 Jupiter masses) around the known seven single white dwarfs in the Hyades cluster at sub-arcsec separations. At an age of 625 Myr, the white dwarfs had progenitor masses of about 3 solar masses, and massive gaseous giant planets should have formed in the massive circumstellar disks around these ex-Herbig A0 stars, probably at orbital separations similar or slightly larger than that of Jupiter. Such planets would have survived the post-Main-Sequence mass loss of the parent star and would have migrated outward adiabatically to a distance of about 25 AU. At the distance of the Hyades (45 pc) this corresponds to an angular separation of 0.5 arcsec. J and H magnitudes of these giants are in the range of 20.5-23.3 mag, which can be resolved with NICMOS. The achieved sensitivities and contrast ratios agree well with simulations. Preliminary evaluation of the NICMOS data set did not reveal any evidence for neither planetary mass companions with masses down to about 10 Jupiter masses nor brown dwarfs around any of the seven white dwarfs for separations larger than 0.5 arcsec., Comment: 14th European Workshop on White Dwarfs
Published: 2005
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40. CHEOPS/ZIMPOL: a VLT instrument study for the polarimetric search of scattered light from extrasolar planets

Author: Gisler, D., Schmid, H.M., Thalmann, C., Povel, H.P., Stenflo, J.O., Joos, F., Feldt, M., Lenzen, R., Tinbergen, J., Gratton, R., Stuik, R., Stam, D.M., Brandner, W., Hippler, S., Turatto, M., Neuhauser, R., Dominik, C., Hatzes, A., Henning, T., Lima, J., Quirrenbach, A., Waters, L.B.F.M., Wuchterl, G., Zinnecker, H., Moorwood, A.F.M., Iye, M., and Low Energy Astrophysics (API, FNWI)
Subjects: Physics, Ccd camera, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Polarimetry, Astronomy, Polarimeter, Polarization (waves), Exoplanet, Optics, Planet, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Scattered light, business
Abstract: We present results from a phase A study supported by ESO for a VLT instrument for the search and investigation of extrasolar planets. The envisaged CHEOPS (CHaracterizing Extrasolar planets by Opto-infrared Polarization and Spectroscopy) instrument consists of an extreme AO system, a spectroscopic integral field unit and an imaging polarimeter. This paper describes the conceptual design of the imaging polarimeter which is based on the ZIMPOL (Zurich IMaging POLarimeter) technique using a fast polarization modulator combined with a demodulating CCD camera. ZIMPOL is capable of detecting polarization signals on the order of p=0.001% as demonstrated in solar applications. We discuss the planned implementation of ZIMPOL within the CHEOPS instrument, in particular the design of the polarization modulator. Further we describe strategies to minimize the instrumental effects and to enhance the overall measuring efficiency in order to achieve the very demanding science goals.
Published: 2004
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41. NGC 3603 - a Local Template for Massive Young Clusters

Author: Brandl, B., Brandner, W., Eisenhauer, F., Moffat, A. F. J., Palla, F., and Zinnecker, H.
Subjects: Astrophysics (astro-ph), Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: We present a study of the star cluster associated with the massive Galactic HII region NGC3603 based on near-IR broad-- and narrowband observations taken with ISAAC/VLT under excellent seeing conditions (, 3 pages, 3 figures. To appear in the Proceedings of IAU Symposium 207 "Extragalactic Star Clusters", eds. E. Grebel, D. Geisler and D. Minitti
Published: 2001
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42. VLT-detection of two edge-on Circumstellar Disks in the rho Oph dark cloud

Author: Brandner, W., Sheppard, S., Zinnecker, H., Close, L., Iwamuro, F., Krabbe, A., Maihara, T., Motohara, K., Padgett, D. L., and Tokunaga, A.
Subjects: Astrophysics (astro-ph), Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: Observations of the rho Ophiuchi star forming region with VLT ANTU and ISAAC under 0.35" seeing conditions reveal two bipolar reflection nebulosities intersected by central dust lanes. The sources (OphE-MM3 and CRBR 2422.8-3423) can be identified as spatially resolved circumstellar disks viewed close to edge-on, similar to edge-on disk sources discovered previously in the Taurus and Orion star forming regions. Millimeter continuum fluxes yield disk masses of the order of 0.01 Mo, i.e. about the mass deemed necessary for the minimum solar nebula. Follow-up spectroscopic observations with SUBARU and CISCO show that both disk sources exhibit featureless continua in the K-band. No accretion or outflow signatures were detected. The slightly less edge-on orientation of the disk around CRBR 2422.8-3423 compared to HH 30 leads to a dramatic difference in the flux seen in the ISOCAM 4.5 mu to 12 mu bands. The observations confirm theoretical predictions on the effect of disk geometry and inclination angle on the spectral energy distribution of young stellar objects with circumstellar disks., Comment: 6 pages, 5 Postscript figures, uses aa.cls and psfig.sty. Astronomy & Astrophysics Letters, in press (December 2000 issue on early science results with the VLT)
Published: 2000
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43. The Peak Brightness and Spatial Distribution of AGB Stars Near the Nucleus of M32

Author: Davidge, T. J., Rigaut, F., Chun, M., Brandner, W., Potter, D., Northcott, M., and Graves, B.
Subjects: Astrophysics (astro-ph), Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: The bright stellar content near the center of the Local Group elliptical galaxy M32 is investigated with 0.12 arcsec FWHM H and K images obtained with the Gemini Mauna Kea telescope. Stars with K = 15.5, which are likely evolving near the tip of the asymptotic giant branch (AGB), are resolved to within 2 arcsec of the nucleus, and it is concluded that the peak stellar brightness near the center of M32 is similar to that in the outer regions of the galaxy. Moreover, the projected density of bright AGB stars follows the visible light profile to within 2 arcsec of the nucleus, indicating that the brightest stars are well mixed throughout the galaxy. Thus, there is no evidence for an age gradient, and the radial variations in spectroscopic indices and ultraviolet colors that have been detected previously must be due to metallicity and/or some other parameter. We suggest that either the bright AGB stars formed as part of a highly uniform and coherent galaxy-wide episode of star formation, or they originated in a separate system that merged with M32., Comment: 9 pages of text, 3 figures. ApJ (Letters) in press
Published: 2000
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44. HST/WFPC2 and VLT/ISAAC observations of PROPLYDS in the giant HII region NGC 3603

Author: Brandner, W., Grebel, E. K., Chu, Y. -H., Dottori, H., Brandl, B., Richling, S., Yorke, H. W., Points, S. D., and Zinnecker, H.
Subjects: Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: We report the discovery of three proplyd-like structures in the giant HII region NGC 3603. The emission nebulae are clearly resolved in narrow-band and broad-band HST/WFPC2 observations in the optical and broad-band VLT/ISAAC observations in the near-infrared. All three nebulae are tadpole shaped, with the bright ionization front at the head facing the central cluster and a fainter ionization front around the tail pointing away from the cluster. Typical sizes are 6,000 A.U. x 20,000 A.U. The nebulae share the overall morphology of the proplyds (``PROto PLanetarY DiskS'') in Orion, but are 20 to 30 times larger in size. Additional faint filaments located between the nebulae and the central ionizing cluster can be interpreted as bow shocks resulting from the interaction of the fast winds from the high-mass stars in the cluster with the evaporation flow from the proplyds. The striking similarity of the tadpole shaped emission nebulae in NGC 3603 to the proplyds in Orion suggests that the physical structure of both types of objects might be the same. We present 2D radiation hydrodynamical simulations of an externally illuminated star-disk-envelope system, which was still in its main accretion phase when first exposed to ionizing radiation from the central cluster. The simulations reproduce the overall morphology of the proplyds in NGC 3603 very well, but also indicate that mass-loss rates of up to 10^-5 Mo/yr are required in order to explain the size of the proplyds. (abbreviated), Comment: 10 pages, 4 Postscript figures, uses emulateapj.sty and psfig.tex. Astronomical Journal, in press (January 2000 issue)
Published: 1999
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45. Discovery of a planetary-mass companion within the gap of the transition disk around PDS 70

Author: Keppler, M., Benisty, M., Müller, A., Henning, Th., Van Boekel, R., Cantalloube, F., Ginski, C., Van Holstein, R. G., Maire, A.-L., Pohl, A., Samland, M., Avenhaus, H., Baudino, J.-L., Boccaletti, A., De Boer, J., Bonnefoy, M., Chauvin, G., Desidera, S., Langlois, M., Lazzoni, C., Marleau, Gabriel-Dominique, Mordasini, Christoph, Pawellek, N., Stolker, T., Vigan, A., Zurlo, A., Birnstiel, T., Brandner, W., Feldt, M., Flock, M., Girard, J., Gratton, R., Hagelberg, J., Isella, A., Janson, M., Juhasz, A., Kemmer, J., Kral, Q., Lagrange, A.-M., Launhardt, R., Matter, A., Ménard, F., Milli, J., Mollière, P., Olofsson, J., Pérez, L., Pinilla, P., Pinte, C., Quanz, S. P., Schmidt, T., Udry, S., Wahhaj, Z., Williams, J. P., Buenzli, E., Cudel, M., Dominik, C., Galicher, R., Kasper, M., Lannier, J., Mesa, D., Mouillet, D., Peretti, S., Perrot, C., Salter, G., Sissa, E., Wildi, F., Abe, L., Antichi, J., Augereau, J.-C., Baruffolo, A., Baudoz, P., Bazzon, A., Beuzit, J.-L., Blanchard, P., Brems, S. S., Buey, T., De Caprio, V., Carbillet, M., Carle, M., Cascone, E., Cheetham, A., Claudi, R., Costille, A., Delboulbé, A., Dohlen, K., Fantinel, D., Feautrier, P., Fusco, T., Giro, E., Gluck, L., Gry, C., Hubin, N., Hugot, E., Jaquet, M., Le Mignant, D., Llored, M., Madec, F., Magnard, Y., Martinez, P., Maurel, D., Meyer, M., Möller-Nilsson, O., Moulin, T., Mugnier, L., Origné, A., Pavlov, A., Perret, D., Petit, C., Pragt, J., Puget, P., Rabou, P., Ramos, J., Rigal, F., Rochat, S., Roelfsema, R., Rousset, G., Roux, A., Salasnich, B., Sauvage, J.-F., Sevin, A., Soenke, C., Stadler, E., Suarez, M., Turatto, M., and Weber, L.
Subjects: 13. Climate action, 530 Physics, 520 Astronomy, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, 500 Science, 620 Engineering, Astrophysics::Galaxy Astrophysics
Abstract: Young circumstellar disks are of prime interest to understand the physical and chemical conditions under which planet formation takes place. Only very few detections of planet candidates within these disks exist, and most of them are currently suspected to be disk features. In this context, the transition disk around the young star PDS 70 is of particular interest, due to its large gap identified in previous observations, indicative of ongoing planet formation. We aim to search for the presence of planets and search for disk structures indicative for disk-planet interactions and other evolutionary processes. We analyse new and archival near-infrared (NIR) images of the transition disk PDS 70 obtained with the VLT/SPHERE, VLT/NaCo and Gemini/NICI instruments in polarimetric differential imaging (PDI) and angular differential imaging (ADI) modes. We detect a point source within the gap of the disk at about 195 mas (about 22 au) projected separation. The detection is confirmed at five different epochs, in three filter bands and using different instruments. The astrometry results in an object of bound nature, with high significance. The comparison of the measured magnitudes and colours to evolutionary tracks suggests that the detection is a companion of planetary mass. We confirm the detection of a large gap of about 54 au in size within the disk in our scattered light images, and detect a signal from an inner disk component. We find that its spatial extent is very likely smaller than about 17 au in radius. The images of the outer disk show evidence of a complex azimuthal brightness distribution which may in part be explained by Rayleigh scattering from very small grains. Future observations of this system at different wavelengths and continuing astrometry will allow us to test theoretical predictions regarding planet-disk interactions, planetary atmospheres and evolutionary models.

46. Age Spread in Galactic star forming region W3 Main

Author: Bik, A., Henning, Th, Stolte, A., Brandner, W., Dimitrios Gouliermis, Gennaro, M., Pasquali, A., Rochau, B., Beuther, H., Ageorges, N., Seifert, W., Wang, Y., and Kudryavtseva, N.
Subjects: Astrophysics of Galaxies (astro-ph.GA), FOS: Physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Astrophysics of Galaxies, Astrophysics::Galaxy Astrophysics
Abstract: We present near-infrared JHKs imaging as well as K-band multi-object spectroscopy of the massive stellar content of W3 Main using LUCI at the LBT. We confirm 13 OB stars by their absorption line spectra in W3 Main and spectral types between O5V and B4V have been found. Three massive Young Stellar Objects are identified by their emission line spectra and near-infrared excess. From our spectrophotometric analysis of the massive stars and the nature of their surrounding HII regions we derive the evolutionary sequence of W3 Main and we find an age spread of 2-3 Myr., 4 pages, 2 figures, To appear in conference proceedings of "370 years of Astronomy in Utrecht"

47. Spectral and atmospheric characterization of 51 Eridani b using VLT/SPHERE

Author: Samland, M., Mollière, P., Bonnefoy, M., Maire, A.-L., Cantalloube, F., Cheetham, A. C., Mesa, D., Gratton, R., Biller, B. A., Wahhaj, Z., Bouwman, J., Brandner, W., Melnick, D., Carson, J., Janson, M., Henning, T., Homeier, D., Mordasini, Christoph, Langlois, M., Quanz, S. P., Van Boekel, R., Zurlo, A., Schlieder, J. E., Avenhaus, H., Beuzit, J.-L., Boccaletti, A., Bonavita, M., Chauvin, G., Claudi, R., Cudel, M., Desidera, S., Feldt, M., Fusco, T., Galicher, R., Kopytova, T. G., Lagrange, A.-M., Le Coroller, H., Martinez, P., Moeller-Nilsson, O., Mouillet, D., Mugnier, L. M., Perrot, C., Sevin, A., Sissa, E., Vigan, A., and Weber, L.
Subjects: 13. Climate action, 530 Physics, 520 Astronomy, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, 500 Science, 620 Engineering, Astrophysics::Galaxy Astrophysics
Abstract: Context. 51 Eridani b is an exoplanet around a young (20 Myr) nearby (29.4 pc) F0-type star, which was recently discovered by direct imaging. It is one of the closest direct imaging planets in angular and physical separation (~0.5′′, ~13 au) and is well suited for spectroscopic analysis using integral field spectrographs. Aims. We aim to refine the atmospheric properties of the known giant planet and to constrain the architecture of the system further by searching for additional companions. Methods. We used the extreme adaptive optics instrument SPHERE at the Very Large Telescope (VLT) to obtain simultaneous dual-band imaging with IRDIS and integral field spectra with IFS, extending the spectral coverage of the planet to the complete Y- to H-band range and providing additional photometry in the K12-bands (2.11, 2.25 μm). The object is compared to other known cool and peculiar dwarfs. The posterior probability distributions for parameters of cloudy and clear atmospheric models are explored using MCMC. We verified our methods by determining atmospheric parameters for the two benchmark brown dwarfs Gl 570D and HD 3651B. We used archival VLT-NACO (L′) Sparse Aperture Masking data to probe the innermost region for additional companions. Results. We present the first spectrophotometric measurements in the Y and K bands for the planet and revise its J-band flux to values 40% fainter than previous measurements. Cloudy models with uniform cloud coverage provide a good match to the data. We derive the temperature, radius, surface gravity, metallicity, and cloud sedimentation parameter fsed. We find that the atmosphere is highly super-solar ([Fe/H] = 1.0 ± 0.1 dex), and the low value is indicative of a vertically extended, optically thick cloud cover with small sized particles. The model radius and surface gravity estimates suggest higher planetary masses of . The evolutionary model only provides a lower mass limit of > 2 MJ (for pure hot-start). The cold-start model cannot explain the luminosity of the planet. The SPHERE and NACO/SAM detection limits probe the 51 Eri system at solar system scales and exclude brown-dwarf companions more massive than 20 MJ beyond separations of ~2.5 au and giant planets more massive than 2 MJ beyond 9 au.

48. A dusty benchmark brown dwarf near the ice line of HD 72946

Author: Alcalá, J. M., Majidi, F. Z., Frasca, A., Manara, C. F., Rigliaco, E., Gratton, R., Covino, E., Claudi, R., D'Orazi, V., Lazzoni, C., Mesa, D., Schlieder, J. E., Vigan, A., D’Orazi, V., Maire, A. -L., Baudino, J. -L., Desidera, S., Messina, S., Brandner, W., Godoy, N., Cantalloube, F., Galicher, R., Bonnefoy, M., Hagelberg, J., Olofsson, J., Absil, O., Chauvin, G., Henning, T., Langlois, M, INAF - Osservatorio Astrofisico di Catania (OACT), Istituto Nazionale di Astrofisica (INAF), INAF - Osservatorio Astronomico di Padova (OAPD), Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, Max Planck Institute for Astronomy (MPIA), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Cardiovasculaire, métabolisme, diabétologie et nutrition (CarMeN), Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Hospices Civils de Lyon (HCL), Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Proper motion, 010504 meteorology & atmospheric sciences, planets and satellites: dynamical evolution and stability, Brown dwarf, FOS: Physical sciences, Context (language use), techniques: image processing, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Luminosity, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), stars: individual: HD 72946, 0105 earth and related environmental sciences, Earth and Planetary Astrophysics (astro-ph.EP), Orbital elements, Physics, [PHYS]Physics [physics], techniques: high angular resolution, Astronomy and Astrophysics, Effective temperature, methods: data analysis, Exoplanet, Radial velocity, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], brown dwarfs, Astrophysics - Earth and Planetary Astrophysics
Abstract: Context. HD72946 is a bright and nearby solar-type star hosting a low-mass companion at long period (P~16 yr) detected with the radial velocities (RV) method. The companion has a minimum mass of 60.4+/-2.2 MJ and might be a brown dwarf. Its expected semi-major axis of ~243 mas makes it a suitable target for further characterization with high-contrast imaging, in particular to measure its inclination, mass, and spectrum and thus definitely establish its substellar nature. Aims. We aim to further characterize the orbit, atmosphere, and physical nature of HD72946B. Methods. We present high-contrast imaging data in the near-infrared with the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument. We also use proper motion measurements of the star from Hipparcos and Gaia. Results. The SPHERE data reveal a point source with a contrast of ~9 mag at a projected separation of ~235 mas. No other point sources are detected in the field of view. By jointly fitting the RV, imaging, and proper motion data, we constrain all the orbital parameters of HD72946B and assess a dynamical mass of 72.4+/-1.6 MJ and a semi-major axis of 6.45$^{+0.08}_{-0.07}$ au. Empirical comparison of its IFS spectrum to template dwarfs indicates a spectral type of L5.0+/-1.5. The J-H3 color is close to the expectations of the DUSTY models and suggests a cloudy atmosphere. Comparison with atmospheric models of the spectrophotometry suggests an effective temperature of ~1700 K. The bolometric luminosity (log(L/LS)=-4.11+/-0.10 dex) and dynamical mass of HD72946B are more compatible with evolutionary models for an age range of ~0.9-3 Gyr. The formation mechanism of the companion is currently unclear as it appears slightly away from the bulk of model predictions. HD72946B is currently the closest benchmark brown dwarf companion to a solar-type star with imaging, RV, and proper motion measurements., Comment: Accepted for publication in A&A, 10 pages, 10 figures, 1 table. Includes language editing. Missing references in Sect. 6 and Appendix E added
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