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1. A family portrait of disk inner rims around Herbig Ae/Be stars: Hunting for warps, rings, self shadowing, and misalignments in the inner astronomical units

Author

Kluska, J., Berger, J. -P., Malbet, F., Lazareff, B., Benisty, M., Bouquin, J. -B. Le, Absil, O., Baron, F., Delboulbé, A., Duvert, G., Isella, A., Jocou, L., Juhasz, A., Kraus, S., Lachaume, R., Ménard, F., Millan-Gabet, R., Monnier, J. D., Moulin, T., Perraut, K., Pinte, C., Rochat, S., Soulez, F., Tallon, M., Thi, W. -F., Thiébaut, E., Traub, W., and Zins, G.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Astrophysics of Galaxies, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

The innermost astronomical unit in protoplanetary disks is a key region for stellar and planet formation, as exoplanet searches have shown a large occurrence of close-in planets that are located within the first au around their host star. We aim to reveal the morphology of the disk inner rim using near-infrared interferometric observations with milli-arcsecond resolution provided by infrared interferometry. We provide reconstructed images of 15 objects selected from the Herbig AeBe survey carried out with PIONIER at the VLTI, using SPARCO. We find that 40% of the systems are centrosymmetric at the angular resolution of the observations. For the rest of the objects, we find evidence for asymmetric emission due to moderate-to-strong inclination of a disk-like structure for 30% of the objects and noncentrosymmetric morphology due to a nonaxisymmetric and possibly variable environment (30%). Among the systems with a disk-like structure, 20% show a resolved dust-free cavity. The image reconstruction process is a powerful tool to reveal complex disk inner rim morphologies. At the angular resolution reached by near-infrared interferometric observations, most of the images are compatible with a centrally peaked emission (no cavity). For the most resolved targets, image reconstruction reveals morphologies that cannot be reproduced by generic parametric models. Moreover, the nonaxisymmetric disks show that the spatial resolution probed by optical interferometers makes the observations of the near-infrared emission sensitive to temporal evolution with a time-scale down to a few weeks. The evidence of nonaxisymmetric emission that cannot be explained by simple inclination and radiative transfer effects requires alternative explanations, such as a warping of the inner disks. Interferometric observations can, therefore, be used to follow the evolution of the asymmetry of those disks at a sub-au scale., Comment: Accepted in A&A, 24pages, 22 figures

Published
2020
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2. The GRAVITY young stellar object survey. II. First spatially resolved observations of the CO bandhead emission in a high-mass YSO

Author

GRAVITY Collaboration, Garatti, A. Caratti o, Fedriani, R., Lopez, R. Garcia, Koutoulaki, M., Perraut, K., Linz, H., Brandner, W., Garcia, P., Klarmann, L., Henning, T., Labadie, L., Sanchez-Bermudez, J., Lazareff, B., van Dishoeck, E. F., Caselli, P., de Zeeuw, P. T., Bik, A., Benisty, M., Dougados, C., Ray, T. P., Amorim, A., Berger, J. -P., Clénet, Y., Foresto, V. Coudé du, Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Gendron, E., Genzel, R., Gillessen, S., Gordo, P., Jocou, L., Horrobin, M., Kervella, P., Lacour, S., Bouquin, J. -B. Le, Léna, P., Grellmann, R., Ott, T., Paumard, T., Perrin, G., Rousset, G., Scheithauer, S., Shangguan, J., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Thi, W. F., Vincent, F. H., and Widmann, F.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies
Abstract

The inner regions of the discs of high-mass young stellar objects (HMYSOs) are still poorly known due to the small angular scales and the high visual extinction involved. We deploy near-infrared (NIR) spectro-interferometry to probe the inner gaseous disc in HMYSOs and investigate the origin and physical characteristics of the CO bandhead emission (2.3-2.4 $\mu$m). We present the first GRAVITY/VLTI observations at high spectral (R=4000) and spatial (mas) resolution of the CO overtone transitions in NGC 2024 IRS2. The continuum emission is resolved in all baselines and is slightly asymmetric, displaying small closure phases ($\leq$8$^{\circ}$). Our best ellipsoid model provides a disc inclination of 34$^{\circ}$$\pm$1$^{\circ}$, a disc major axis position angle of 166$^{\circ}$$\pm$1$^{\circ}$, and a disc diameter of 3.99$\pm$0.09 mas (or 1.69$\pm$0.04 au, at a distance of 423 pc). The small closure phase signals in the continuum are modelled with a skewed rim, originating from a pure inclination effect. For the first time, our observations spatially and spectrally resolve the first four CO bandheads. Changes in visibility, as well as differential and closure phases across the bandheads are detected. Both the size and geometry of the CO-emitting region are determined by fitting a bidimensional Gaussian to the continuum-compensated CO bandhead visibilities. The CO-emitting region has a diameter of 2.74$\pm^{0.08}_{0.07}$ mas (1.16$\pm$0.03 au), and is located in the inner gaseous disc, well within the dusty rim, with inclination and $PA$ matching the dusty disc geometry, which indicates that both dusty and gaseous discs are coplanar. Physical and dynamical gas conditions are inferred by modelling the CO spectrum. Finally, we derive a direct measurement of the stellar mass of $M_*\sim$14.7$^{+2}_{-3.6}$ M$_{\odot}$ by combining our interferometric and spectral modelling results., Comment: Accepted for publication in A&A letters

Published
2020
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3. The GRAVITY Young Stellar Object survey -- I. Probing the disks of Herbig Ae/Be stars in terrestrial orbits

Author

Perraut, K., Labadie, L., Lazareff, B., Klarmann, L., Segura-Cox, D., Benisty, M., Bouvier, J., Brandner, W., Garatti, A. Caratti o, 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., Foresto, V. Coudé du, 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., Bouquin, J. -B. Le, 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., and Yazici, S.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Astrophysics of Galaxies
Abstract

The formation and the evolution of protoplanetary disks are important stages in the lifetime of stars. The processes of disk evolution and planet formation are intrinsically linked. We spatially resolve with GRAVITY/VLTI in the K-band the sub au-scale region of 27 stars to gain statistical understanding of their properties. We look for correlations with stellar parameters, such as luminosity, mass, temperature and age. 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. Our best models correspond to smooth and wide rings, implying that wedge-shaped rims at the dust sublimation edge are favored, as found in the H-band. The closure phases are generally non-null with a median value of ~10 deg, indicating spatial asymmetries of the intensity distributions. Multi-size grain populations could explain the closure phase ranges below 20-25 deg but other scenarios should be invoked to explain the largest ones. Our measurements extend the Radius-Luminosity relation to ~1e4 Lsun and confirm the significant spread around the mean relation observed 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 2 Ms mass range, we 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 HAeBe mass range. The measured locations of the K-band emission suggest that these disks might be structured by forming young planets, rather than by depletion due to EUV, FUV, and X-ray photo-evaporation., Comment: Accepted for publication in A&A; 23 pages, 16 figures, 7 tables

Published
2019
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4. Detection of orbital motions near the last stable circular orbit of the massive black hole SgrA*

Author

GRAVITY Collaboration, Abuter, R., Amorim, A., Bauböck, M., Berger, J. P., Bonnet, H., Brandner, W., Clénet, Y., Foresto, V. Coudé du, de Zeeuw, P. T., Deen, C., Dexter, J., Duvert, G., Eckart, A., Eisenhauer, F., Schreiber, N. M. Förster, Garcia, P., Gao, F., Gendron, E., Genzel, R., Gillessen, S., Guajardo, P., Habibi, M., Haubois, X., Henning, Th., Hippler, S., Horrobin, M., Huber, A., Jiménez-Rosales, A., Jocou, L., Kervella, P., Lacour, S., Lapeyrère, V., Lazareff, B., Bouquin, J. -B. Le, Léna, P., Lippa, M., Ott, T., Panduro, J., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Plewa, P. M., Rabien, S., Rodríguez-Coira, G., Rousset, G., 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., and Yazici, S.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

We report the detection of continuous positional and polarization changes of the compact source SgrA* in high states ('flares') of its variable near- infrared emission with the near-infrared GRAVITY-Very Large Telescope Interferometer (VLTI) beam-combining instrument. In three prominent bright flares, the position centroids exhibit clockwise looped motion on the sky, on scales of typically 150 micro-arcseconds over a few tens of minutes, corresponding to about 30% the speed of light. At the same time, the flares exhibit continuous rotation of the polarization angle, with about the same 45(+/-15)-minute period as that of the centroid motions. Modelling with relativistic ray tracing shows that these findings are all consistent with a near face-on, circular orbit of a compact polarized 'hot spot' of infrared synchrotron emission at approximately six to ten times the gravitational radius of a black hole of 4 million solar masses. This corresponds to the region just outside the innermost, stable, prograde circular orbit (ISCO) of a Schwarzschild-Kerr black hole, or near the retrograde ISCO of a highly spun-up Kerr hole. The polarization signature is consistent with orbital motion in a strong poloidal magnetic field., Comment: accepted by A&A; 16 pages

Published
2018
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5. 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., and Zins, G.

Subjects
Astrophysics - Solar and Stellar Astrophysics
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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6. Detection of the gravitational redshift in the orbit of the star S2 near the Galactic centre massive black hole

Author

GRAVITY Collaboration, Abuter, R., Amorim, A., Anugu, N., Bauböck, M., Benisty, M., Berger, J. P., Blind, N., Bonnet, H., Brandner, W., Buron, A., Collin, C., Chapron, F., Clénet, Y., Foresto, V. Coudé du, de Zeeuw, P. T., Deen, C., Delplancke-Ströbele, F., Dembet, R., Dexter, J., Duvert, G., Eckart, A., Eisenhauer, F., Finger, G., Schreiber, N. M. Förster, Fédou, P., Garcia, P., Lopez, R. Garcia, Gao, F., Gendron, E., Genzel, R., Gillessen, S., Gordo, P., Habibi, M., Haubois, X., Haug, M., Haußmann, F., Henning, Th., Hippler, S., Horrobin, M., Hubert, Z., Hubin, N., Rosales, A. Jimenez, Jochum, L., Jocou, L., Kaufer, A., Kellner, S., Kendrew, S., Kervella, P., Kok, Y., Kulas, M., Lacour, S., Lapeyrère, V., Lazareff, B., Bouquin, J. -B. Le, Léna, P., Lippa, M., Lenzen, R., Mérand, A., Müller, E., Neumann, U., Ott, T., Palanca, L., Paumard, T., Pasquini, L., Perraut, K., Perrin, G., Pfuhl, O., Plewa, P. M., Rabien, S., Ramírez, A., Ramos, J., Rau, C., Rodríguez-Coira, G., Rohloff, R. -R., Rousset, G., Sanchez-Bermudez, J., Scheithauer, S., Schöller, M., Schuler, N., Spyromilio, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., Tristram, K. R. W., Vincent, F., von Fellenberg, S., Wank, I., Waisberg, I., Widmann, F., Wieprecht, E., Wiest, M., Wiezorrek, E., Woillez, J., Yazici, S., Ziegler, D., and Zins, G.

Subjects
Astrophysics - Astrophysics of Galaxies, General Relativity and Quantum Cosmology, Physics - Classical Physics
Abstract

The highly elliptical, 16-year-period orbit of the star S2 around the massive black hole candidate Sgr A* is a sensitive probe of the gravitational field in the Galactic centre. Near pericentre at 120 AU, ~1400 Schwarzschild radii, the star has an orbital speed of ~7650 km/s, such that the first-order effects of Special and General Relativity have now become detectable with current capabilities. Over the past 26 years, we have monitored the radial velocity and motion on the sky of S2, mainly with the SINFONI and NACO adaptive optics instruments on the ESO Very Large Telescope, and since 2016 and leading up to the pericentre approach in May 2018, with the four-telescope interferometric beam-combiner instrument GRAVITY. From data up to and including pericentre, we robustly detect the combined gravitational redshift and relativistic transverse Doppler effect for S2 of z ~ 200 km/s / c with different statistical analysis methods. When parameterising the post-Newtonian contribution from these effects by a factor f, with f = 0 and f = 1 corresponding to the Newtonian and general relativistic limits, respectively, we find from posterior fitting with different weighting schemes f = 0.90 +/- 0.09 (stat) +\- 0.15 (sys). The S2 data are inconsistent with pure Newtonian dynamics., Comment: Accepted for publication in A&A Letters, 29 June 2018, 10 pages, 6 figures, corresponding author: F. Eisenhauer

Published
2018
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7. The wind and the magnetospheric accretion onto the T Tauri star S Coronae Australis at sub-au resolution

Author

Lopez, R. Garcia, Perraut, K., Garatti, A. Caratti o, Lazareff, B., Sanchez-Bermudez, J., Benisty, M., Dougados, C., Labadie, L., Brandner, W., Garcia, P. J. V., Henning, Th., Ray, T. P., Abuter, R., Amorim, A., Anugu, N., Berger, J. P., Bonnet, H., Buron, A., Caselli, P., Clénet, Y., Foresto, V. Coudé du, de Wit, W., Deen, C., Delplancke-Ströbele, F., Dexter, J., Eckart, A., Eisenhauer, F., Dabo, C. E. Garcia, Gendron, E., Genzel, R., Gillessen, S., Haubois, X., Haug, M., Haussmann, F., Hippler, S., Hubert, Z., Hummel, C. A., Horrobin, M., Jocou, L., Kellner, S., Kervella, P., Kulas, M., Kolb, J., Lacour, S., Bouquin, J. -B. Le, Léna, P., Lippa, M, Mérand, A., Müller, E., Ott, T., Panduro, J., Paumard, T., Perrin, G., Pfuhl, O., Ramirez, A., Rau, C., Rohloff, R. -R., Rousset, G., Scheithauer, S., Schöller, M., Straubmeier, C., Sturm, E., Thi, W. F., van Dishoeck, E., Vincent, F., Waisberg, I., Wank, I., Wieprecht, E., Wiest, M., Wiezorrek, E., Woillez, J., Yazici, S., and Zins, G.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

To investigate the inner regions of protoplanetary disks, we performed near-infrared interferometric observations of the classical TTauri binary system S CrA. We present the first VLTI-GRAVITY high spectral resolution ($R\sim$4000) observations of a classical TTauri binary, S CrA (composed of S CrA N and S CrA S and separated by $\sim$1.4"), combining the four 8-m telescopes in dual-field mode. Our observations in the near-infrared K-band continuum reveal a disk around each binary component, with similar half-flux radii of about 0.1 au at d$\sim$130 pc, inclinations ($i=$28$\pm$3$^o$\ and $i=$22$\pm$6$^o$), and position angles (PA=0$^o\pm$6$^o$ and PA=-2$^o\pm$12$^o$), suggesting that they formed from the fragmentation of a common disk. The S CrA N spectrum shows bright HeI and Br$\gamma$ line emission exhibiting inverse P-Cygni profiles, typically associated with infalling gas. The continuum-compensated Br$\gamma$ line visibilities of S CrA N show the presence of a compact Br$\gamma$ emitting region the radius of which is about $\sim$0.06 au, which is twice as big as the truncation radius. This component is mostly tracing a wind. Moreover, a slight radius change between the blue- and red-shifted Br$\gamma$ line components is marginally detected. The presence of an inverse P-Cygni profile in the HeI and Br$\gamma$ lines, along with the tentative detection of a slightly larger size of the blue-shifted Br$\gamma$ line component, hint at the simultaneous presence of a wind and magnetospheric accretion in S CrA N., Comment: Accepted by A&A

Published
2017
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8. Accretion-ejection morphology of the microquasar SS433 resolved at sub-au scale

Author

GRAVITY Collaboration, Petrucci, P. -O., Waisberg, I., Bouquin, J. -B. Le, Dexter, J., Dubus, G., Perraut, K., Kervella, P., Abuter, R., Amorim, A., Anugu, N., Berger, J. P., Blind, N., Bonnet, H., Brandner, W., Buron, A., Choquet, É., Clénet, Y., de Wit, W., Deen, C., Eckart, A., Eisenhauer, F., Finger, G., Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Gonte, F., Haubois, X., Haug, M., Haussmann, F., Henning, Th., Hippler, S., Horrobin, M., Hubert, Z., Jochum, L., Jocou, L., Kok, Y., Kolb, J., Kulas, M., Lacour, S., Lazareff, B., Lèna, P., Lippa, M., Mérand, A., Müller, E., Ott, T., Panduro, J., Paumard, T., Perrin, G., Pfuhl, O., Ramos, J., Rau, C., Rohloff, R. -R., Rousset, G., Sanchez-Bermudez, J., Scheithauer, S., Schöller, M., Straubmeier, C., Sturm, E., Vincent, F., Wank, I., Wieprecht, E., Wiest, M., Wiezorrek, E., Wittkowski, M., Woillez, J., Yazici, S., and Zins, G.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Solar and Stellar Astrophysics
Abstract

We present the first optical observation at sub-milliarcsecond (mas) scale of the microquasar SS 433 obtained with the GRAVITY instrument on the VLT interferometer. The 3.5 hour exposure reveals a rich K-band spectrum dominated by hydrogen Br$\gamma\ $ and \ion{He}{i} lines, as well as (red-shifted) emission lines coming from the jets. The K-band continuum emitting region is dominated by a marginally resolved point source ($<$ 1 mas) embedded inside a diffuse background accounting for 10\% of the total flux. The jet line positions agree well with the ones expected from the jet kinematic model, an interpretation also supported by the consistent sign (i.e. negative/positive for the receding/approaching jet component) of the phase shifts observed in the lines. The significant visibility drop across the jet lines, together with the small and nearly identical phases for all baselines, point toward a jet that is offset by less than 0.5 mas from the continuum source and resolved in the direction of propagation, with a typical size of 2 mas. The jet position angle of $\sim$80$^{\circ}$ is consistent with the expected one at the observation date. Jet emission so close to the central binary system would suggest that line locking, if relevant to explain the amplitude and stability of the 0.26c jet velocity, operates on elements heavier than hydrogen. The Br$\gamma\ $ profile is broad and double peaked. It is better resolved than the continuum and the change of the phase signal sign across the line on all baselines suggests an East-West oriented geometry alike the jet direction and supporting a (polar) disk wind origin., Comment: Submitted for publication in A&A Letters, 4 pages + appendix, 4 figures. Comments welcome

Published
2017
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9. First Light for GRAVITY: Phase Referencing Optical Interferometry for the Very Large Telescope Interferometer

Author

GRAVITY Collaboration, Abuter, R., Accardo, M., Amorim, A., Anugu, N., Ávila, G., Azouaoui, N., Benisty, M., Berger, J. P., Blind, N., Bonnet, H., Bourget, P., Brandner, W., Brast, R., Buron, A., Burtscher, L., Cassaing, F., Chapron, F., Choquet, É., Clénet, Y., Collin, C., Foresto, V. Coudé du, de Wit, W., de Zeeuw, P. T., Deen, C., Delplancke-Ströbele, F., Dembet, R., Derie, F., Dexter, J., Duvert, G., Ebert, M., Eckart, A., Eisenhauer, F., Esselborn, M., Fédou, P., Finger, G., Garcia, P., Dabo, C. E. Garcia, Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Gonte, F., Gordo, P., Grould, M., Grözinger, U., Guieu, S., Haguenauer, P., Hans, O., Haubois, X., Haug, M., Haussmann, F., Henning, Th., Hippler, S., Horrobin, M., Huber, A., Hubert, Z., Hubin, N., Hummel, C. A., Jakob, G., Janssen, A., Jochum, L., Jocou, L., Kaufer, A., Kellner, S., Kern, L., Kervella, P., Kiekebusch, M., Klein, R., Kok, Y., Kolb, J., Kulas, M., Lacour, S., Lapeyrère, V., Lazareff, B., Bouquin, J. -B. Le, Lèna, 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., Perrin, G., Pflüger, A., Pfuhl, O., Duc, T. Phan, Plewa, P. M., Popovic, D., Rabien, S., Ramírez, A., Ramos, J., Rau, C., Riquelme, M., Rohloff, R. -R., Rousset, G., Sanchez-Bermudez, J., Scheithauer, S., Schöller, M., Schuhler, N., Spyromilio, J., Straubmeier, C., Sturm, E., Suarez, M., Tristram, K. R. W., Ventura, N., Vincent, F., Waisberg, I., Wank, I., Weber, J., Wieprecht, E., Wiest, M., Wiezorrek, E., Wittkowski, M., Woillez, J., Wolff, B., Yazici, S., Ziegler, D., and Zins, G.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

GRAVITY is a new instrument to coherently combine the light of the European Southern Observatory Very Large Telescope Interferometer to form a telescope with an equivalent 130 m diameter angular resolution and a collecting area of 200 m$^2$. The instrument comprises fiber fed integrated optics beam combination, high resolution spectroscopy, built-in beam analysis and control, near-infrared wavefront sensing, phase-tracking, dual beam operation and laser metrology [...]. This article gives an overview of GRAVITY and reports on the performance and the first astronomical observations during commissioning in 2015/16. We demonstrate phase tracking on stars as faint as m$_K$ ~ 10 mag, phase-referenced interferometry of objects fainter than m$_K$ ~ 15 mag with a limiting magnitude of m$_K$ ~ 17 mag, minute long coherent integrations, a visibility accuracy of better than 0.25 %, and spectro-differential phase and closure phase accuracy better than 0.5{\deg}, corresponding to a differential astrometric precision of better than 10 microarcseconds ({\mu}as). The dual-beam astrometry, measuring the phase difference of two objects with laser metrology, is still under commissioning. First observations show residuals as low as 50 {\mu}as when following objects over several months. We illustrate the instrument performance with the observations of archetypical objects for the different instrument modes. Examples include the Galactic Center supermassive black hole and its fast orbiting star S2 for phase referenced dual beam observations and infrared wavefront sensing, the High Mass X-Ray Binary BP Cru and the Active Galactic Nucleus of PDS 456 for few {\mu}as spectro-differential astrometry, the T Tauri star S CrA for a spectro-differential visibility analysis, {\xi} Tel and 24 Cap for high accuracy visibility observations, and {\eta} Car for interferometric imaging with GRAVITY., Comment: Accepted for publication in A&A, 23 pages, 23 figures, corresponding author: F. Eisenhauer

Published
2017
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10. Interferometric Evidence for Quantum Heated Particles in the Inner Region of Protoplanetary Disks around Herbig Stars

Author

Klarmann, L., Benisty, M., Min, M., Dominik, C., Berger, J. -P., Waters, L. B. F. M., Kluska, J., Lazareff, B., and Bouquin, J. -B. Le

Subjects
Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Solar and Stellar Astrophysics
Abstract

To understand the chemical composition of planets, it is important to know the chemical composition of the region where they form in protoplanetary disks. Due to its fundamental role in chemical and biological processes, carbon is a key element to trace. We aim to identify the carriers and processes behind the extended NIR flux observed around several Herbig stars. We compare the extended NIR flux from objects in the PIONIER Herbig Ae/Be survey with their flux in the PAH features. HD 100453 is used as a benchmark case to investigate the influence of quantum heated particles, like PAHs or very small carbonaceous grains, in more detail. We use the Monte Carlo radiative transfer code MCMax to do a parameter study of the QHP size and scale- height and examine the influence of quantum heating on the amount of extended flux in the NIR visibilities. There is a correlation between the PAH feature flux of a disk and the amount of its extended NIR flux. We find that very small carbonaceous grains create the observed extended NIR flux around HD 100453 and still lead to a realistic SED. These results can not be achieved without using quantum heating effects, e.g. only with scattered light and grains in thermal equilibrium. It is possible to explain the extended NIR emission around Herbig stars with the presence of carbonaceous, quantum heated particles. Interferometric observations can be used to constrain the spatial distribution and typical size of carbonaceous material in the terrestrial planet forming region., Comment: 10 pages, 6 figures, 2 tables, accepted for publication at A&A

Published
2016
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11. Structure of Herbig AeBe disks at the milliarcsecond scale A statistical survey in the H band using PIONIER-VLTI

Author

Lazareff, B., Berger, J. -P., Kluska, J., Bouquin, J. -B. Le, Benisty, M., Malbet, F., Koen, C., Pinte, C., Thi, W. -F., Absil, O., Baron, F., Delboulbé, A., Duvert, G., Isella, A., Jocou, L., Juhasz, A., Kraus, S., Lachaume, R., Ménard, F., Millan-Gabet, R., Monnier, J. D., Moulin, T., Perraut, K., Rochat, S., Soulez, F., Tallon, M., Thiébaut, E., Traub, W., and Zins, G.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

Context. It is now generally accepted that the near-infrared excess of Herbig AeBe stars originates in the dust of a circumstellar disk. Aims. The aims of this article are to infer the radial and vertical structure of these disks at scales of order one au, and the properties of the dust grains. Methods. The program objects (51 in total) were observed with the H-band (1.6micron) PIONIER/VLTI interferometer. The largest baselines allowed us to resolve (at least partially) structures of a few tenths of an au at typical distances of a few hundred parsecs. Dedicated UBVRIJHK photometric measurements were also obtained. Spectral and 2D geometrical parameters are extracted via fits of a few simple models: ellipsoids and broadened rings with azimuthal modulation. Model bias is mitigated by parallel fits of physical disk models. Sample statistics were evaluated against similar statistics for the physical disk models to infer properties of the sample objects as a group. Results. We find that dust at the inner rim of the disk has a sublimation temperature Tsub~1800K. A ring morphology is confirmed for approximately half the resolved objects; these rings are wide delta_r>=0.5. A wide ring favors a rim that, on the star-facing side, looks more like a knife edge than a doughnut. The data are also compatible with a the combination of a narrow ring and an inner disk of unspecified nature inside the dust sublimation radius. The disk inner part has a thickness z/r~0.2, flaring to z/r~0.5 in the outer part. We confirm the known luminosity-radius relation; a simple physical model is consistent with both the mean luminosity-radius relation and the ring relative width; however, a significant spread around the mean relation is present. In some of the objects we find a halo component, fully resolved at the shortest interferometer spacing, that is related to the HAeBe class., Comment: 41 pages. 23 figures. Four appendices

Published
2016
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12. A disk asymmetry in motion around the B[e] star MWC158

Author

Kluska, J., Benisty, M., Soulez, F., Berger, J. -P., Bouquin, J. -B. Le, Malbet, F., Lazareff, B., and Thiébaut, E.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

MWC158 is a star with the B[e] phenomenon that shows strong spectrophotometric variability (in lines and in UV and visible continuum) attributed to phases of shell ejection. The evolutionary stage of this star was never clearly determined. Previous interferometric, spectropolarimetric and spectro-interferometric studies suggest a disk morphology for its environment. We investigate the origin of the variability within the inner astronomical unit of the central star using near-infrared interferometric observations with PIONIER at the VLTI over a two-year period. We performed an image reconstruction of the circumstellar environment using the SPARCO method. We discovered that the morphology of the circumstellar environment could vary on timescales of weeks or days. We carried out a parametric fit of the data with a model consisting of a star, a disk and a bright spot that represents a brighter emission in the disk. We detect strong morphological changes in the first astronomical unit around the star, that happen on a timescale of few months. We cannot account for such variability well with a binary model. Our parametric model fits the data well and allows us to extract the location of the asymmetry for different epochs. For the first time, we detect a morphological variability in the environment of MWC158. This variability is reproduced by a model of a disk and a bright spot. The locations of the bright spot suggest that it is located in the disk, but its precise motion is not determined. The origin of the asymmetry in the disk is complex and may be related to asymmetric shell ejections., Comment: Accepted for publication in A&A

Published
2016
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13. Reaching micro-arcsecond astrometry with long baseline optical interferometry; application to the GRAVITY instrument

Author

Lacour, S., Eisenhauer, F., Gillessen, S., Pfuhl, O., Woillez, J., Bonnet, H., Perrin, G., Lazareff, B., Rabien, S., Lapeyrere, V., Clenet, Y., Kervella, P., and Kok, Y.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

A basic principle of long baseline interferometry is that an optical path difference (OPD) directly translates into an astrometric measurement. In the simplest case, the OPD is equal to the scalar product between the vector linking the two telescopes and the normalized vector pointing toward the star. However, a too simple interpretation of this scalar product leads to seemingly conflicting results, called here "the baseline paradox". For micro-arcsecond accuracy astrometry, we have to model in full the metrology measurement. It involves a complex system subject to many optical effects: from pure baseline errors to static, quasi-static and high order optical aberrations. The goal of this paper is to present the strategy used by the "General Relativity Analysis via VLT InTerferometrY" instrument (GRAVITY) to minimize the biases introduced by these defects. It is possible to give an analytical formula on how the baselines and tip-tilt errors affect the astrometric measurement. This formula depends on the limit-points of three type of baselines: the wide-angle baseline, the narrow-angle baseline, and the imaging baseline. We also, numerically, include non-common path higher-order aberrations, whose amplitude were measured during technical time at the Very Large Telescope Interferometer. We end by simulating the influence of high-order common-path aberrations due to atmospheric residuals calculated from a Monte-Carlo simulation tool for Adaptive optics systems. The result of this work is an error budget of the biases caused by the multiple optical imperfections, including optical dispersion. We show that the beam stabilization through both focal and pupil tracking is crucial to the GRAVITY system. Assuming the instrument pupil is stabilized at a 4 cm level on M1, and a field tracking below 0.2$\lambda/D$, we show that GRAVITY will be able to reach its objective of 10$\mu$as accuracy., Comment: 14 pages. Accepted by A&A

Published
2014
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14. SPARCO : a semi-parametric approach for image reconstruction of chromatic objects

Author

Kluska, J., Malbet, F., Berger, J. -P., Baron, F., Lazareff, B., Bouquin, J. -B. Le, Monnier, J. D., Soulez, F., and Thiébaut, E.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Solar and Stellar Astrophysics
Abstract

The emergence of optical interferometers with three and more telescopes allows image reconstruction of astronomical objects at the milliarcsecond scale. However, some objects contain components with very different spectral energy distributions (SED; i.e. different temperatures), which produces strong chromatic effects on the interferograms that have to be managed with care by image reconstruction algorithms. For example, the gray approximation for the image reconstruction process results in a degraded image if the total (u, v)-coverage given by the spectral supersynthesis is used. The relative flux contribution of the central object and an extended structure changes with wavelength for different temperatures. For young stellar objects, the known characteristics of the central object (i.e., stellar SED), or even the fit of the spectral index and the relative flux ratio, can be used to model the central star while reconstructing the image of the extended structure separately. Methods. We present a new method, called SPARCO (semi-parametric algorithm for the image reconstruction of chromatic objects), which describes the spectral characteristics of both the central object and the extended structure to consider them properly when reconstructing the image of the surrounding environment. We adapted two image-reconstruction codes (Macim, Squeeze, and MiRA) to implement this new prescription. SPARCO is applied using Macim, Squeeze and MiRA on a young stellar object model and also on literature data on HR5999 in the near-infrared with the VLTI. This method paves the way to improved aperture-synthesis imaging of several young stellar objects with existing datasets. More generally, the approach can be used on astrophysical sources with similar features such as active galactic nuclei, planetary nebulae, and asymptotic giant branch stars., Comment: 11 pages, 11 figures, accepted in A&A

Published
2014
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15. Roche-lobe filling factor of mass-transferring red giants - the PIONIER view

Author

Boffin, Henri M. J., Hillen, M., Berger, J. P., Jorissen, A., Blind, N., Bouquin, J. B. Le, Mikolajewska, J., and Lazareff, B.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

Using the PIONIER visitor instrument that combines the light of the four Auxiliary Telescopes of ESO's Very Large Telescope Interferometer, we measure precisely the diameters of several symbiotic and related stars: HD 352, HD 190658, V1261 Ori, ER Del, FG Ser, and AG Peg. These diameters - in the range of 0.6 to 2.3 milli-arcseconds - are used to assess the filling factor of the Roche lobe of the mass-losing giants and provide indications on the nature of the ongoing mass transfer. We also provide the first spectroscopic orbit of ER Del, based on CORAVEL and HERMES/Mercator observations. The system is found to have an eccentric orbit with a period of 5.7 years. In the case of the symbiotic star FG Ser, we find that the diameter is changing by 13% over the course of 41 days, while the observations of HD 352 are indicative of an elongation. Both these stars are found to have a Roche filling factor close to 1, as is most likely the case for HD 190658 as well, while the three other stars have factors below 0.5-0.6. Our observations reveal the power of interferometry for the study of interacting binary stars - the main limitation in our conclusions being the poorly known distances of the objects., Comment: A&A, in press

Published
2014
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16. The close environment of high-mass X-ray binaries at high angular resolution I. VLTI/AMBER and VLTI/PIONIER near-infrared interferometric observations of Vela X-1

Author

Choquet, E., Kervella, P., Bouquin, J. -B. Le, Merand, A., Berger, J. -P., Haubois, X., Perrin, G., Petrucci, P. -O., Lazareff, B., and Pott, J. -U.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

Recent improvements on the sensitivity and spectral resolution of X-ray observations have led to a better understanding of the properties of matter in the vicinity of High Mass X-ray Binaries hosting a supergiant star and a compact object. However the geometry and physical properties of their environment at larger scales are currently only predicted by simulations. We aim at exploring the environment of Vela X-1 at a few stellar radii of the supergiant using spatially resolved observations in the near-infrared and at studying its dynamical evolution along the 9-day orbital period of the system. We observed Vela X-1 in 2010 and 2012 using long baseline interferometry at VLTI, respectively with the AMBER instrument in the K band and the PIONIER instrument in the H band. The PIONIER observations span through one orbital period to monitor possible evolutions in the geometry of the system. We resolved a structure of $8\pm3~R_\star$ from the AMBER data and $2.0\,_{-1.2}^{+0.7}~R_\star$ from the PIONIER data. From the closure phase we found that the environment of Vela X-1 is symmetrical. We observed comparable measurements between the continuum and the spectral lines in the K band, meaning that both emissions originate from the same forming region. From the monitoring of the system over one period in 2012, we found the signal to be constant with the orbital phase within the error bars. We propose three scenarios for the discrepancy between the two measurements: either there is a strong temperature gradient in the supergiant wind leading to a hot component much more compact than the cool part of the wind observed in the K band, or we observed a diffuse shell in 2010 possibly triggered by an off-state in the accretion rate of the pulsar that was dissolved in the interstellar medium in 2012, or the structure observed in the H band was the stellar photosphere instead of the supergiant wind., Comment: Accepted for publication in A&A

Published
2013
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17. PIONIER: a status report

Author

Bouquin, J. -B. Le, Berger, J. -P., Zins, G., Lazareff, B., Jocou, L., Kern, P., Millan-Gabet, R., Traub, W., Haguenauer, P., Absil, O., Augereau, J. -C., Benisty, M., Blind, N., Delboulbe, A., Feautrier, P., Germain, M., Gillier, D., Gitton, P., Kiekebusch, M., Knudstrup, J., Lizon, J. -L, Magnard, Y., Malbet, F., Maurel, D., Menard, F., Micallef, M., Michaud, L., Moulin, T., Popovic, D., Perraut, K., Rabou, P., Rochat, S., Roussel, F., Roux, A., Stadler, E., and Tatulli, E.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

The visitor instrument PIONIER provides VLTI with improved imaging capabilities and sensitivity. The instrument started routinely delivering scientific data in November 2010, that is less than 12 months after being approved by the ESO Science and Technical Committee. We recall the challenges that had to be tackled to design, built and commission PIONIER. We summarize the typical performances and some astrophysical results obtained so far. We conclude this paper by summarizing lessons learned., Comment: To appear in the proceedings of the 2012 SPIE Conference "Astronomical Telescopes and Instrumentation"

Published
2012
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18. An incisive look at the symbiotic star SS Leporis -- Milli-arcsecond imaging with PIONIER/VLTI

Author

Blind, N., Boffin, H. M. J., Berger, J. -P., Bouquin, J. -B. Le, Mérand, A., Lazareff, B., and Zins, G.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

Context. Determining the mass transfer in a close binary system is of prime importance for understanding its evolution. SS Leporis, a symbiotic star showing the Algol paradox and presenting clear evidence of ongoing mass transfer, in which the donor has been thought to fill its Roche lobe, is a target particularly suited to this kind of study. Aims. Since previous spectroscopic and interferometric observations have not been able to fully constrain the system morphology and characteristics, we go one step further to determine its orbital parameters, for which we need new interferometric observations directly probing the inner parts of the system with a much higher number of spatial frequencies. Methods. We use data obtained at eight different epochs with the VLTI instruments AMBER and PIONIER in the H- and K-bands. We performed aperture synthesis imaging to obtain the first model-independent view of this system. We then modelled it as a binary (whose giant is spatially resolved) that is surrounded by a circumbinary disc. Results. Combining these interferometric measurements with previous radial velocities, we fully constrain the orbit of the system. We then determine the mass of each star and significantly revise the mass ratio. The M giant also appears to be almost twice smaller than previously thought. Additionally, the low spectral resolution of the data allows the flux of both stars and of the dusty disc to be determined along the H and K bands, and thereby extracting their temperatures. Conclusions. We find that the M giant actually does not stricto sensus fill its Roche lobe. The mass transfer is more likely to occur through the accretion of an important part of the giant wind. We finally rise the possibility for an enhanced mass loss from the giant, and we show that an accretion disc should have formed around the A star., Comment: 11 pages, 5 figures, published in A&A Appendix presenting reduced data and extracted parameters Reduced data can be found on the CDS

Published
2011
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19. PIONIER: a 4-telescope visitor instrument at VLTI

Author

Bouquin, Jean-Baptiste Le, Berger, J. -P., Lazareff, B., Zins, G., Haguenauer, P., Jocou, L., Kern, P., Millan-Gabet, R., Traub, W., Absil, O., Augereau, J. -C., Benisty, M., Blind, N., Bonfils, X., Bourget, P., Delboulbe, A., Feautrier, P., Germain, M., Gitton, P., Gillier, D., Kiekebusch, M., Kluska, J., Knudstrup, J., Labeye, P., Lizon, J. -L., Monin, J. -L., Magnard, Y., Malbet, F., Maurel, D., Menard, F., Micallef, M., Michaud, L., Montagnier, G., Morel, S., Moulin, T., Perraut, K., Popovic, D., Rabou, P., Rochat, S., Rojas, C., Roussel, F., Roux, A., Stadler, E., Stefl, S., Tatulli, E., and Ventura, N.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

PIONIER stands for Precision Integrated-Optics Near-infrared Imaging ExpeRiment. It combines four 1.8m Auxilliary Telescopes or four 8m Unit Telescopes of the Very Large Telescope Interferometer (ESO, Chile) using an integrated optics combiner. The instrument has been integrated at IPAG starting in December 2009 and commissioned at the Paranal Observatory in October 2010. It provides scientific observations since November 2010. In this paper, we detail the instrumental concept, we describe the standard operational modes and the data reduction strategy. We present the typical performance and discuss how to improve them. This paper is based on laboratory data obtained during the integrations at IPAG, as well as on-sky data gathered during the commissioning at VLTI. We illustrate the imaging capability of PIONIER on the binaries deltaSco and HIP11231. PIONIER provides 6 visibilities and 3 independent closure phases in the H band, either in a broadband mode or with a low spectral dispersion (R=40), using natural light (i.e. unpolarized). The limiting magnitude is Hmag=7 in dispersed mode under median atmospheric conditions (seeing<1", tau0>3ms) with the 1.8m Auxiliary Telescopes. We demonstrate a precision of 0.5deg on the closure phases. The precision on the calibrated visibilities ranges from 3 to 15% depending on the atmospheric conditions. PIONIER has been installed and successfully tested as a visitor instrument for the VLTI. It permits high angular resolution imaging studies at an unprecedented level of sensitivity. The successful combination of the four 8m Unit Telescopes in March 2011 demonstrates that VLTI is ready for 4-telescope operation.

Published
2011
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20. PIONIER: a visitor instrument for the VLTI

Author

Berger, J. -P., Zins, G., Lazareff, B., Lebouquin, J. -B., Jocou, L., Kern, P., Millan-Gabet, R., Traub, W., Haguenauer, P., Absil, O., Augereau, J. -C., Benisty, M., Blind, N., Bonfils, X., Delboulbe, A., Feautrier, P., Germain, M., Gillier, D., Gitton, P., Kiekebusch, M., Knudstrup, J., Lizon, J. -L, Magnard, Y., Malbet, F., Maurel, D., Menard, F., Micallef, M., Michaud, L., Morel, S., Moulin, T., Popovic, D., Perraut, K., Rabou, P., Rochat, S., Roussel, F., Roux, A., Stadler, E., and Tatulli, E.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

PIONIER is a 4-telescope visitor instrument for the VLTI, planned to see its first fringes in 2010. It combines four ATs or four UTs using a pairwise ABCD integrated optics combiner that can also be used in scanning mode. It provides low spectral resolution in H and K band. PIONIER is designed for imaging with a specific emphasis on fast fringe recording to allow closure-phases and visibilities to be precisely measured. In this work we provide the detailed description of the instrument and present its updated status., Comment: Proceedings of SPIE conference Optical and Infrared Interferometry II (Conference 7734) San Diego 2010

Published
2010
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23. The GRAVITY young stellar object survey : II. First spatially resolved observations of the CO bandhead emission in a high-mass YSO

Author

Garatti, A. Caratti O., Fedriani, R., Lopez, R. Garcia, Koutoulaki, M., Perraut, K., Linz, H., Brandner, W., Garcia, P., Klarmann, L., Henning, T., Labadie, L., Sanchez-Bermudez, J., Lazareff, B., van Dishoeck, E. F., Caselli, P., de Zeeuw, P. T., Bik, Adrianus, Benisty, M., Dougados, C., Ray, T. P., Amorim, A., Berger, J-P, Clenet, Y., du Foresto, V. Coude, Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Gendron, E., Genzel, R., Gillessen, S., Gordo, P., Jocou, L., Horrobin, M., Kervella, P., Lacour, S., Le Bouquin, J-B, Lena, P., Grellmann, R., Ott, T., Paumard, T., Perrin, G., Rousset, G., Scheithauer, S., Shangguan, J., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Thi, W. F., Vincent, F. H., Widmann, F., Garatti, A. Caratti O., Fedriani, R., Lopez, R. Garcia, Koutoulaki, M., Perraut, K., Linz, H., Brandner, W., Garcia, P., Klarmann, L., Henning, T., Labadie, L., Sanchez-Bermudez, J., Lazareff, B., van Dishoeck, E. F., Caselli, P., de Zeeuw, P. T., Bik, Adrianus, Benisty, M., Dougados, C., Ray, T. P., Amorim, A., Berger, J-P, Clenet, Y., du Foresto, V. Coude, Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Gendron, E., Genzel, R., Gillessen, S., Gordo, P., Jocou, L., Horrobin, M., Kervella, P., Lacour, S., Le Bouquin, J-B, Lena, P., Grellmann, R., Ott, T., Paumard, T., Perrin, G., Rousset, G., Scheithauer, S., Shangguan, J., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Thi, W. F., Vincent, F. H., and Widmann, F.

Abstract

Context. The inner regions of the discs of high-mass young stellar objects (HMYSOs) are still poorly known due to the small angular scales and the high visual extinction involved.Aims. We deploy near-infrared spectro-interferometry to probe the inner gaseous disc in HMYSOs and investigate the origin and physical characteristics of the CO bandhead emission (2.3-2.4 mu m).Methods. We present the first GRAVITY/VLTI observations at high spectral (R=4000) and spatial (mas) resolution of the CO overtone transitions in NGC 2024 IRS 2.Results. The continuum emission is resolved in all baselines and is slightly asymmetric, displaying small closure phases (<= 8 degrees). Our best ellipsoid model provides a disc inclination of 34 degrees +/- 1 degrees, a disc major axis position angle (PA) of 166 degrees +/- 1 degrees, and a disc diameter of 3.99 +/- 0.09 mas (or 1.69 +/- 0.04 au, at a distance of 423 pc). The small closure phase signals in the continuum are modelled with a skewed rim, originating from a pure inclination effect. For the first time, our observations spatially and spectrally resolve the first four CO bandheads. Changes in visibility, as well as differential and closure phases across the bandheads are detected. Both the size and geometry of the CO-emitting region are determined by fitting a bidimensional Gaussian to the continuum-compensated CO bandhead visibilities. The CO-emitting region has a diameter of 2.74 +/-(0.08)(0.07) +/- 0.07 0.08 mas (1.16 +/- 0.03 au), and is located in the inner gaseous disc, well within the dusty rim, with inclination and PA matching the dusty disc geometry, which indicates that both dusty and gaseous discs are coplanar. Physical and dynamical gas conditions are inferred by modelling the CO spectrum. Finally, we derive a direct measurement of the stellar mass of M-* similar to 14.7(-3.6)(+2)M(circle dot) M * similar to 14 . 7 - 3.6 + 2 M circle dot by combining our interferometric and spectral modelling resu

Published
2020
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25. A family portrait of disk inner rims around Herbig Ae/Be stars

Author

Kluska, J., primary, Berger, J.-P., additional, Malbet, F., additional, Lazareff, B., additional, Benisty, M., additional, Le Bouquin, J.-B., additional, Absil, O., additional, Baron, F., additional, Delboulbé, A., additional, Duvert, G., additional, Isella, A., additional, Jocou, L., additional, Juhasz, A., additional, Kraus, S., additional, Lachaume, R., additional, Ménard, F., additional, Millan-Gabet, R., additional, Monnier, J. D., additional, Moulin, T., additional, Perraut, K., additional, Rochat, S., additional, Pinte, C., additional, Soulez, F., additional, Tallon, M., additional, Thi, W.-F., additional, Thiébaut, E., additional, Traub, W., additional, and Zins, G., additional

Published
2020
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26. Hunting Exoplanets with Single-Mode Optical Interferometry

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::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

The GRAVITY instrument was primarily conceived for imaging and astrometry of the Galactic centre. However, its sensitivity and astrometric capabilities have also enabled interferometry to reach a new domain of astrophysics: exoplanetology. In March 2019, the GRAVITY collaboration published the first spectrum and astrometry of an exoplanet obtained by optical interferometry. In this article, we show how this observation is paving the way to even more exciting discoveries — finding new planets, and characterising their atmospheres., Published in The Messenger vol. 178, pp. 47-49, December 2019.

Published
2019
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27. 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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28. 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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30. Spatially Resolving the Quasar Broad Emission Line Region

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.H., Cantalloube, F., Caratti, O, Garatti, A., Caselli, P., Cassaing, F., Chapron, F., Charnay, B., Choquet, É., 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., Zeeuw, T. de, 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., Boekel, R. van, Dishoeck, E.F. van, 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
General Relativity and Quantum Cosmology, [SDU]Sciences of the Universe [physics], Astrophysics::High Energy Astrophysical Phenomena, 0103 physical sciences, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 010303 astronomy & astrophysics, 01 natural sciences, Astrophysics::Galaxy Astrophysics
Abstract

The angular resolution of the Very Large Telescope Interferometer (VLTI) and the excellent sensitivity of GRAVITY have led to the first detection of spatially resolved kinematics of high velocity atomic gas near an accreting super- massive black hole, revealing rotation on sub-parsec scales in the quasar 3C 273 at a distance of 550 Mpc. The observations can be explained as the result of circular orbits in a thick disc configuration around a 300 million solar mass black hole. Within an ongoing Large Programme, this capability will be used to study the kinematics of atomic gas and its relation to hot dust in a sample of quasars and Seyfert galaxies. We will measure a new radius-luminosity relation from spatially resolved data and test the current methods used to measure black hole mass in large surveys., Published in The Messenger vol. 178, pp. 20-24, December 2019.

Published
2019
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31. 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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32. 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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33. 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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34. 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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38. 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

39. GRAVITY - Reaching out to SgrA* with VLTI

Author

Abuter, R., Amorim, A., Anugu, N, Bauböck, M, Benisty, M., Berger, J., Blind, N., Bonnet, H, Brandner, W., Buron, A, Collin, C., Chapron, F., Clénet, Y., Coudé Du Foresto, V., De Zeeuw, P, Deen, C, Delplancke-Ströbele, F, Dembet, R., Dexter, J, Duvert, G., Eckart, A., Eisenhauer, F., Finger, G, Förster Schreiber, N, Fédou, P, GARCIA, P, Garcia Lopez, R, Gao, F, Gendron, E, Genzel, R, Gillessen, S, Gordo, P, Habibi, M, Haubois, X, Haug, M, Haußmann, F, Henning, Th, Hippler, S, Horrobin, M., Hubert, Z, Hubin, N, Rosales, A, Jochum, L, Jocou, L, Kaufer, A, Kellner, S, Kendrew, S, Kervella, P, Kok, Y, Kulas, M, Lacour, S, Lapeyrère, V, Lazareff, B, Le Bouquin, J.-B, Léna, P, Lippa, M, Lenzen, R, Mérand, A, Müler, E, Neumann, U, Ott, T, Palanca, L, Paumard, T, Pasquini, L, Perraut, K, Perrin, G, Pfuhl, O, Plewa, P, Rabien, S, Ramírez, A, Ramos, J, Rau, C, Rodríguez-Coira, G, Rohloff, R.-R, Rousset, G, Sanchez-Bermudez, J, Scheithauer, S, Schöller, M, Schuler, N, Spyromilio, J, Straub, O, Straubmeier, C., Sturm, E, Tacconi, L, Tristram, K, Vincent, F, Von Fellenberg, S, Wank, I, Waisberg, I, Widmann, F, Wieprecht, E, Wiest, M, Wiezorrek, E, Woillez, J, Yazici, S, Ziegler, D, Zins, G, European Southern Observatory (ESO), SIM/IDL Faculdade de Ciências da Universidade de Lisboa (FCUL), University of 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), STMicroelectronics [Crolles] (ST-CROLLES), Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, 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), 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), Max-Planck-Institut für Radioastronomie (MPIFR), Max Planck Institute for Extraterrestrial Physics (MPE), Universität zu Köln, 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 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 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.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], [SDU]Sciences of the Universe [physics]
Abstract

International audience; As one of the 2nd generation of interferometric instruments in VLTI, GRAVITY was in-stalled at the end of 2015 and has been observing the Galactic Center since May 2016. Withthe goal to reach an accuracy of tens of micro arcseconds, it is able to perform the mostprecise astrometric measurement of SgrA* to date. For that purpose, GRAVITY combinesthe light collected (coherently) from of all the 8 m UTs or the four 1.8 m ATs providing in-frared wavefront sensing to control the telescope adaptive optics, two interferometric beamcombiners (one for fringe-tracking and one for the science object), an acquisition cameraand various laser guiding systems for beam stabilization, as well as a dedicated laser metrol-ogy to trace the optical path length differences for narrow angle astrometry. Operating inK band with an active stabilization of the science channel, GRAVITY is able to increasethe typical integration time from a few milliseconds (the typical atmospheric coherencetime) to minutes, which implies a big leap in sensitivity allowing to observe fainter objects(K=19 in science detector) with the power of a 130m baseline interferometer, as it is theclose environment of the supermassive black hole located in the center of our Galaxy.

Published
2018

40. 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

41. Multiple star systems in the Orion nebula

Author

Collaboration, G., Karl, M., Pfuhl, O., Eisenhauer, F., Genzel, R., Grellmann, R., Habibi, M., Abuter, R., Accardo, M., Amorim, A., Anugu, N., Ávila, G., Benisty, M., Berger, J., Blind, N., Bonnet, H., Bourget, P., Brandner, W., Brast, R., Buron, A., Caratti O Garatti, A., Chapron, F., 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., Esselborn, M., Fédou, P., Finger, G., Garcia, P., Garcia Dabo, C., Garcia Lopez, R., Gao, F., Gendron, É., Gillessen, S., Gonté, F., Gordo, P., Grözinger, U., Guajardo, P., Guieu, S., Haguenauer, P., Hans, O., Haubois, X., Haug, M., Haußmann, F., Henning, T., Hippler, S., Horrobin, M., Huber, A., Hubert, Z., Hubin, N., Jakob, G., Jochum, L., Jocou, L., Kaufer, A., Kellner, S., Kendrew, S., Kern, L., Kervella, P., Kiekebusch, M., Klein, R., Köhler, R., Kolb, J., Kulas, M., Lacour, S., Lapeyrère, V., Lazareff, B., Le Bouquin, J., Léna, P., Lenzen, R., Lévêque, S., Lin, C., Lippa, M., Magnard, Y., Mehrgan, L., Mérand, A., Moulin, T., Müller, E., Müller, F., Neumann, U., Oberti, S., Ott, T., Pallanca, L., Panduro, J., Pasquini, L., Paumard, T., Percheron, I., Perraut, K., Perrin, G., Pflüger, A., Duc, T., Plewa, P., Popovic, D., Rabien, S., Ramírez, A., Ramos, J., Rau, C., Riquelme, M., Rodríguez-Coira, G., Rohloff, R., Rosales, A., Rousset, G., Sanchez-Bermudez, J., Scheithauer, S., Schöller, M., 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.

Abstract

This work presents an interferometric study of the massive-binary fraction in the Orion Trapezium cluster with the recently comissioned GRAVITY instrument. We observed a total of 16 stars of mainly OB spectral type. We find three previously unknown companions for θ1 Ori B, θ2 Ori B, and θ2 Ori C. We determined a separation for the previously suspected companion of NU Ori. We confirm four companions for θ1 Ori A, θ1 Ori C, θ1 Ori D, and θ2 Ori A, all with substantially improved astrometry and photometric mass estimates. We refined the orbit of the eccentric high-mass binary θ1 Ori C and we are able to derive a new orbit for θ1 Ori D. We find a system mass of 21.7 M☉ and a period of 53 days. Together with other previously detected companions seen in spectroscopy or direct imaging, eleven of the 16 high-mass stars are multiple systems. We obtain a total number of 22 companions with separations up to 600 AU. The companion fraction of the early B and O stars in our sample is about two, significantly higher than in earlier studies of mostly OB associations. The separation distribution hints toward a bimodality. Such a bimodality has been previously found in A stars, but rarely in OB binaries, which up to this point have been assumed to be mostly compact with a tail of wider companions. We also do not find a substantial population of equal-mass binaries. The observed distribution of mass ratios declines steeply with mass, and like the direct star counts, indicates that our companions follow a standard power law initial mass function. Again, this is in contrast to earlier findings of flat mass ratio distributions in OB associations. We excluded collision as a dominant formation mechanism but find no clear preference for core accretion or competitive accretion.

Published
2018

42. Detection of the gravitational redshift in the orbit of the star S2 near the Galactic centre massive black hole

Author

Abuter, R., Amorim, A., Anugu, N., Bauboeck, M., Benisty, M., Berger, J. P., Blind, N., Bonnet, H., Brandner, W., Buron, A., Collin, C., Chapron, F., Clenet, Y., du Foresto, V. Coude, de Zeeuw, P. T., Deen, C., Delplancke-Stroebele, F., Dembet, R., Dexter, J., Duvert, G., Eckart, A., Eisenhauer, F., Finger, G., Schreiber, N. M. Foerster, Fedou, P., Garcia, P., Lopez, R. Garcia, Gao, F., Gendron, E., Genzel, R., Gillessen, S., Gordo, P., Habibi, M., Haubois, X., Haug, M., Haussmann, F., Henning, Th, Hippler, S., Horrobin, M., Hubert, Z., Hubin, N., Rosales, A. Jimenez, Jochum, L., Jocou, L., Kaufer, A., Kellner, S., Kendrew, S., Kervella, P., Kok, Y., Kulas, M., Lacour, S., Lapeyrere, V, Lazareff, B., Le Bouquin, J-B, Lena, P., Lippa, M., Lenzen, R., Merand, A., Mueller, E., Neumann, U., Ott, T., Palanca, L., Paumard, T., Pasquini, L., Perraut, K., Perrin, G., Pfuhl, O., Plewa, P. M., Rabien, S., Ramirez, A., Ramos, J., Rau, C., Rodriguez-Coira, G., Rohloff, R-R, Rousset, G., Sanchez-Bermudez, J., Scheithauer, S., Schoeller, M., Schuler, N., Spyromilio, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., Tristram, K. R. W., Vincent, F., von Fellenberg, S., Wank, I, Waisberg, I, Widmann, F., Wieprecht, E., Wiest, M., Wiezorrek, E., Woillez, J., Yazici, S., Ziegler, D., Zins, G., Abuter, R., Amorim, A., Anugu, N., Bauboeck, M., Benisty, M., Berger, J. P., Blind, N., Bonnet, H., Brandner, W., Buron, A., Collin, C., Chapron, F., Clenet, Y., du Foresto, V. Coude, de Zeeuw, P. T., Deen, C., Delplancke-Stroebele, F., Dembet, R., Dexter, J., Duvert, G., Eckart, A., Eisenhauer, F., Finger, G., Schreiber, N. M. Foerster, Fedou, P., Garcia, P., Lopez, R. Garcia, Gao, F., Gendron, E., Genzel, R., Gillessen, S., Gordo, P., Habibi, M., Haubois, X., Haug, M., Haussmann, F., Henning, Th, Hippler, S., Horrobin, M., Hubert, Z., Hubin, N., Rosales, A. Jimenez, Jochum, L., Jocou, L., Kaufer, A., Kellner, S., Kendrew, S., Kervella, P., Kok, Y., Kulas, M., Lacour, S., Lapeyrere, V, Lazareff, B., Le Bouquin, J-B, Lena, P., Lippa, M., Lenzen, R., Merand, A., Mueller, E., Neumann, U., Ott, T., Palanca, L., Paumard, T., Pasquini, L., Perraut, K., Perrin, G., Pfuhl, O., Plewa, P. M., Rabien, S., Ramirez, A., Ramos, J., Rau, C., Rodriguez-Coira, G., Rohloff, R-R, Rousset, G., Sanchez-Bermudez, J., Scheithauer, S., Schoeller, M., Schuler, N., Spyromilio, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., Tristram, K. R. W., Vincent, F., von Fellenberg, S., Wank, I, Waisberg, I, Widmann, F., Wieprecht, E., Wiest, M., Wiezorrek, E., Woillez, J., Yazici, S., Ziegler, D., and Zins, G.

Abstract

The highly elliptical, 16-year-period orbit of the star S2 around the massive black hole candidate Sgr A* is a sensitive probe of the gravitational field in the Galactic centre. Near pericentre at 120 AU approximate to 1400 Schwarzschild radii, the star has an orbital speed of approximate to 7650 km s(-1), such that the first-order effects of Special and General Relativity have now become detectable with current capabilities. Over the past 26 years, we have monitored the radial velocity and motion on the sky of S2, mainly with the SINFONI and NACO adaptive optics instruments on the ESO Very Large Telescope, and since 2016 and leading up to the pericentre approach in May 2018, with the four-telescope interferometric beam-combiner instrument GRAVITY. From data up to and including pericentre, we robustly detect the combined gravitational redshift and relativistic transverse Doppler effect for S2 of z = Delta lambda/lambda approximate to 200 km s(-1)/c with different statistical analysis methods. When parameterising the post-Newtonian contribution from these effects by a factor f, with f = 0 and f = 1 corresponding to the Newtonian and general relativistic limits, respectively, we find from posterior fitting with different weighting schemes f = 0.90 +/- 0.09 vertical bar(stat) +/- 0.151 vertical bar(sys). The S2 data are inconsistent with pure Newtonian dynamics.

Published
2018

43. Detection of orbital motions near the last stable circular orbit of the massive black hole SgrA*

Author

Abuter, R., Amorim, A., Bauboeck, M., Berger, J. P., Bonnet, H., Brandner, W., Clenet, Y., du Foresto, V. Coude, de Zeeuw, P. T., Deen, C., Dexter, J., Duvert, G., Eckart, A., Eisenhauer, F., Schreiber, N. M. Forster, Garcia, P., Gao, F., Gendron, E., Genzel, R., Gillessen, S., Guajardo, P., Habibi, M., Haubois, X., Henning, Th., Hippler, S., Horrobin, M., Huber, A., Jimenez-Rosales, A., Jocou, L., Kervella, P., Lacour, S., Lapeyrere, V., Lazareff, B., Le Bouquin, J. -B., Lena, P., Lippa, M., Ott, T., Panduro, J., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Plewa, P. M., Rabien, S., Rodriguez-Coira, G., Rousset, G., 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., Abuter, R., Amorim, A., Bauboeck, M., Berger, J. P., Bonnet, H., Brandner, W., Clenet, Y., du Foresto, V. Coude, de Zeeuw, P. T., Deen, C., Dexter, J., Duvert, G., Eckart, A., Eisenhauer, F., Schreiber, N. M. Forster, Garcia, P., Gao, F., Gendron, E., Genzel, R., Gillessen, S., Guajardo, P., Habibi, M., Haubois, X., Henning, Th., Hippler, S., Horrobin, M., Huber, A., Jimenez-Rosales, A., Jocou, L., Kervella, P., Lacour, S., Lapeyrere, V., Lazareff, B., Le Bouquin, J. -B., Lena, P., Lippa, M., Ott, T., Panduro, J., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Plewa, P. M., Rabien, S., Rodriguez-Coira, G., Rousset, G., 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., and Yazici, S.

Abstract

We report the detection of continuous positional and polarization changes of the compact source SgrA* in high states (flares) of its variable near-infrared emission with the near-infrared GRAVITY-Very Large Telescope Interferometer (VLTI) beam-combining instrument. In three prominent bright flares, the position centroids exhibit clockwise looped motion on the sky, on scales of typically 150 mu as over a few tens of minutes, corresponding to about 30% the speed of light. At the same time, the flares exhibit continuous rotation of the polarization angle, with about the same 45(+/- 15) min period as that of the centroid motions. Modelling with relativistic ray tracing shows that these findings are all consistent with a near face-on, circular orbit of a compact polarized hot spot of infrared synchrotron emission at approximately six to ten times the gravitational radius of a black hole of 4 million solar masses. This corresponds to the region just outside the innermost, stable, prograde circular orbit (ISCO) of a Schwarzschild-Kerr black hole, or near the retrograde ISCO of a highly spun-up Kerr hole. The polarization signature is consistent with orbital motion in a strong poloidal magnetic field.

Published
2018

44. GRAVITY chromatic imaging of eta Car's core Milliarcsecond resolution imaging of the wind-wind collision zone (Br gamma, He i)

Author

Sanchez-Bermudez, J., Weigelt, G., Bestenlehner, J. M., Kervella, P., Brandner, W., Henning, Th, 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. Caratti O., Cassaing, F., Chapron, F., Choquet, E., Clenet, Y., Collin, C., du Foresto, V. Coude, 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. 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., 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., Sanchez-Bermudez, J., Weigelt, G., Bestenlehner, J. M., Kervella, P., Brandner, W., Henning, Th, 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. Caratti O., Cassaing, F., Chapron, F., Choquet, E., Clenet, Y., Collin, C., du Foresto, V. Coude, 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. 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., 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., and Zins, G.

Abstract

Context. eta 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 similar to 5-50 au structure of eta Car's wind-wind interaction, as seen through Br gamma 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 epsilon = 1.06 +/- 0.05 over a PA = 130 degrees +/- 20 degrees. 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 Br gamma and He i lines. Chromatic images across the Br gamma 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 (similar to 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

Published
2018

45. Modelling and performance of Nb SIS mixers in the 1.3 mm and 0.8 mm bands

Author

Karpov, A, Carter, M, Lazareff, B, Billon-Pierron, D, and Gundlach, K. H

Subjects
Electronics And Electrical Engineering
Abstract

We describe the modeling and subsequent improvements of SIS waveguide mixers for the 200-270 and 330-370 GHz bands (Blundell, Carter, and Gundlach 1988, Carter et al 1991). These mixers are constructed for use in receivers on IRAM radiotelescopes on Pico Veleta (Spain, Sierra Nevada) and Plateau de Bure (French Alps), and must meet specific requirements. The standard reduced height waveguide structure with suspended stripline is first analyzed and a model is validated through comparison with scale model and working scale measurements. In the first step, the intrinsic limitations of the standard mixer structure are identified, and the parameters are optimized bearing in mind the radioastronomical applications. In the second step, inductive tuning of the junctions is introduced and optimized for minimum noise and maximum bandwidth. In the 1.3 mm band, a DSB receiver temperature of less than 110 K (minimum 80 K) is measured from 180 through 260 GHz. In the 0.8 mm band, a DSB receiver temperature of less than 250 K (minimum 175 K) is obtained between 325 and 355 GHz. All these results are obtained with room-temperature optics and a 4 GHz IF chain having a 500 MHz bandwidth and a noise temperature of 14 K.

Published
1992

46. The GRAVITY young stellar object survey: II. First spatially resolved observations of the CO bandhead emission in a high-mass YSO.

Author

Garatti, A. Caratti o, Fedriani, R., Lopez, R. Garcia, Koutoulaki, M., Perraut, K., Linz, H., Brandner, W., Garcia, P., Klarmann, L., Henning, T., Labadie, L., Sanchez-Bermudez, J., Lazareff, B., van Dishoeck, E. F., Caselli, P., de Zeeuw, P. T., Bik, A., Benisty, M., Dougados, C., and Ray, T. P.

Subjects
GRAVITY, STELLAR mass, MASS measurement, GEOMETRY, STAR formation, BIPOLAR outflows (Astrophysics), INTERFEROMETRY
Abstract

Context. The inner regions of the discs of high-mass young stellar objects (HMYSOs) are still poorly known due to the small angular scales and the high visual extinction involved. Aims. We deploy near-infrared spectro-interferometry to probe the inner gaseous disc in HMYSOs and investigate the origin and physical characteristics of the CO bandhead emission (2.3-2.4 m). Methods. We present the first GRAVITY/VLTI observations at high spectral (R = 4000) and spatial (mas) resolution of the CO overtone transitions in NGC2024 IRS 2. Results. The continuum emission is resolved in all baselines and is slightly asymmetric, displaying small closure phases (≤8°). Our best ellipsoid model provides a disc inclination of 34° ± 1° a disc major axis position angle (PA) of 166° ± 1° and a disc diameter of 3:99 ± 0:09 mas (or 1.69 ± 0.04 au, at a distance of 423 pc). The small closure phase signals in the continuum are modelled with a skewed rim, originating from a pure inclination effect. For the first time, our observations spatially and spectrally resolve the first four CO bandheads. Changes in visibility, as well as differential and closure phases across the bandheads are detected. Both the size and geometry of the CO-emitting region are determined by fitting a bidimensional Gaussian to the continuum-compensated CO bandhead visibilities. The CO-emitting region has a diameter of 2.74±0:08 0:07 mas (1.16 ± 0.03 au), and is located in the inner gaseous disc, well within the dusty rim, with inclination and PA matching the dusty disc geometry, which indicates that both dusty and gaseous discs are coplanar. Physical and dynamical gas conditions are inferred by modelling the CO spectrum. Finally, we derive a direct measurement of the stellar mass of M• ~ 14:7+2 -3:6 M⊙ by combining our interferometric and spectral modelling results. [ABSTRACT FROM AUTHOR]

Published
2020
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47. First light for GRAVITY: Phase referencing optical interferometry for the Very Large Telescope Interferometer

Author

Abuter, R., Accardo, M., Amorim, A., Anugu, N., Avila, G., Azouaoui, N., Benisty, M., Berger, J. P., Blind, N., Bonnet, H., Bourget, P., Brandner, W., Brast, R., Buron, A., Burtscher, L., Cassaing, F., Chapron, F., Choquet, E., Clenet, Y., Collin, C., du Foresto, V. Coude, de Wit, W., de Zeeuw, P. T., Deen, C., Delplancke-Stroebele, F., Dembet, R., Derie, F., Dexter, J., Duvert, G., Ebert, M., Eckart, A., Eisenhauer, F., Esselborn, M., Fedou, P., Finger, G., Garcia, P., Dabo, C. E. Garcia, Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Gonte, F., Gordo, P., Grould, M., Groezinger, U., Guieu, S., Haguenauer, P., Hans, O., Haubois, X., Haug, M., Haussmann, F., Henning, Th., Hippler, S., Horrobin, M., Huber, A., Hubert, Z., Hubin, N., Hummel, C. A., Jakob, G., Janssen, A., Jochum, L., Jocou, L., Kaufer, A., Kellner, S., Kendrew, S., Kern, L., Kervella, P., Kiekebusch, M., Klein, R., Kok, Y., 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., Perrin, G., Pflueger, A., Pfuhl, O., Duc, T. Phan, Plewa, P. M., Popovic, D., Rabien, S., Ramirez, A., Ramos, J., Rau, C., Riquelme, M., Rohloff, R. -R., Rousset, G., Sanchez-Bermudez, J., Scheithauer, S., Schoeller, M., Schuhler, N., Spyromilio, J., Straubmeier, C., Sturm, E., Suarez, M., Tristram, K. R. W., Ventura, N., Vincent, F., Waisberg, I., Wank, I., Weber, J., Wieprecht, E., Wiest, M., Wiezorrek, E., Wittkowski, M., Woillez, J., Wolff, B., Yazici, S., Ziegler, D., Zins, G., Abuter, R., Accardo, M., Amorim, A., Anugu, N., Avila, G., Azouaoui, N., Benisty, M., Berger, J. P., Blind, N., Bonnet, H., Bourget, P., Brandner, W., Brast, R., Buron, A., Burtscher, L., Cassaing, F., Chapron, F., Choquet, E., Clenet, Y., Collin, C., du Foresto, V. Coude, de Wit, W., de Zeeuw, P. T., Deen, C., Delplancke-Stroebele, F., Dembet, R., Derie, F., Dexter, J., Duvert, G., Ebert, M., Eckart, A., Eisenhauer, F., Esselborn, M., Fedou, P., Finger, G., Garcia, P., Dabo, C. E. Garcia, Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Gonte, F., Gordo, P., Grould, M., Groezinger, U., Guieu, S., Haguenauer, P., Hans, O., Haubois, X., Haug, M., Haussmann, F., Henning, Th., Hippler, S., Horrobin, M., Huber, A., Hubert, Z., Hubin, N., Hummel, C. A., Jakob, G., Janssen, A., Jochum, L., Jocou, L., Kaufer, A., Kellner, S., Kendrew, S., Kern, L., Kervella, P., Kiekebusch, M., Klein, R., Kok, Y., 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., Perrin, G., Pflueger, A., Pfuhl, O., Duc, T. Phan, Plewa, P. M., Popovic, D., Rabien, S., Ramirez, A., Ramos, J., Rau, C., Riquelme, M., Rohloff, R. -R., Rousset, G., Sanchez-Bermudez, J., Scheithauer, S., Schoeller, M., Schuhler, N., Spyromilio, J., Straubmeier, C., Sturm, E., Suarez, M., Tristram, K. R. W., Ventura, N., Vincent, F., Waisberg, I., Wank, I., Weber, J., Wieprecht, E., Wiest, M., Wiezorrek, E., Wittkowski, M., Woillez, J., Wolff, B., Yazici, S., Ziegler, D., and Zins, G.

Abstract

GRAVITY is a new instrument to coherently combine the light of the European Southern Observatory Very Large Telescope Interferometer to form a telescope with an equivalent 130m diameter angular resolution and a collecting area of 200 m(2). The instrument comprises fiber fed integrated optics beam combination, high resolution spectroscopy, built-in beam analysis and control, near-infrared wavefront sensing, phase-tracking, dual-beam operation, and laser metrology. GRAVITY opens up to optical/infrared interferometry the techniques of phase referenced imaging and narrow angle astrometry, in many aspects following the concepts of radio interferometry. This article gives an overview of GRAVITY and reports on the performance and the first astronomical observations during commissioning in 2015/16. We demonstrate phase-tracking on stars as faint as m(K) approximate to 10 mag, phase-referenced interferometry of objects fainter than m(K) approximate to 15 mag with a limiting magnitude of m(K) approximate to 17 mag, minute long coherent integrations, a visibility accuracy of better than 0.25%, and spectro-differential phase and closure phase accuracy better than 0.5 degrees, corresponding to a differential astrometric precision of better than ten microarcseconds (as). The dual-beam astrometry, measuring the phase difference of two objects with laser metrology, is still under commissioning. First observations show residuals as low as 50 mu as when following objects over several months. We illustrate the instrument performance with the observations of archetypical objects for the different instrument modes. Examples include the Galactic center supermassive black hole and its fast orbiting star S2 for phase referenced dual-beam observations and infrared wavefront sensing, the high mass X-ray binary BP Cru and the active galactic nucleus of PDS 456 for a few mu as spectro-differential astrometry, the T Tauri star S CrA for a spectro-differential visibility analysis, xi Tel and 24

Published
2017

48. Accretion-ejection morphology of the microquasar SS 433 resolved at sub-au scale

Author

Petrucci, P. -O., Waisberg, I., Le Bouquin, J. -B., Dexter, J., Dubus, G., Perraut, K., Kervella, P., Abuter, R., Amorim, A., Anugu, N., Berger, J. P., Blind, N., Bonnet, H., Brandner, W., Buron, A., Choquet, E., Clenet, Y., de Wit, W., Deen, C., Eckart, A., Eisenhauer, F., Finger, G., Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Gonte, F., Haubois, X., Haug, M., Haussmann, F., Henning, Th., Hippler, S., Horrobin, M., Hubert, Z., Jochum, L., Jocou, L., Kok, Y., Kolb, J., Kulas, M., Lacour, S., Lazareff, B., Lena, P., Lippa, M., Merand, A., Mueller, E., Ott, T., Panduro, J., Paumard, T., Perrin, G., Pfuhl, O., Ramos, J., Rau, C., Rohlo, R. -R., Rousset, G., Sanchez-Bermudez, J., Scheithauer, S., Schoeller, M., Straubmeier, C., Sturm, E., Vincent, F., Wank, I., Wieprecht, E., Wiest, M., Wiezorrek, E., Wittkowski, M., Woillez, J., Yazici, S., Zins, G., Petrucci, P. -O., Waisberg, I., Le Bouquin, J. -B., Dexter, J., Dubus, G., Perraut, K., Kervella, P., Abuter, R., Amorim, A., Anugu, N., Berger, J. P., Blind, N., Bonnet, H., Brandner, W., Buron, A., Choquet, E., Clenet, Y., de Wit, W., Deen, C., Eckart, A., Eisenhauer, F., Finger, G., Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Gonte, F., Haubois, X., Haug, M., Haussmann, F., Henning, Th., Hippler, S., Horrobin, M., Hubert, Z., Jochum, L., Jocou, L., Kok, Y., Kolb, J., Kulas, M., Lacour, S., Lazareff, B., Lena, P., Lippa, M., Merand, A., Mueller, E., Ott, T., Panduro, J., Paumard, T., Perrin, G., Pfuhl, O., Ramos, J., Rau, C., Rohlo, R. -R., Rousset, G., Sanchez-Bermudez, J., Scheithauer, S., Schoeller, M., Straubmeier, C., Sturm, E., Vincent, F., Wank, I., Wieprecht, E., Wiest, M., Wiezorrek, E., Wittkowski, M., Woillez, J., Yazici, S., and Zins, G.

Abstract

We present the first optical observation of the microquasar SS 433 at sub-milliarcsecond (mas) scale obtained with the GRAVITY instrument on the Very Large Telescope interferometer (VLTI). The 3.5-h exposure reveals a rich K-band spectrum dominated by hydrogen Br gamma and He i lines, as well as (red-shifted) emission lines coming from the jets. The K-band-continuum-emitting region is dominated by a marginally resolved point source (<1 mas) embedded inside a diffuse background accounting for 10% of the total flux. The jet line positions agree well with the ones expected from the jet kinematic model, an interpretation also supported by the consistent sign (i.e., negative/positive for the receding/approaching jet component) of the phase shifts observed in the lines. The significant visibility drop across the jet lines, together with the small and nearly identical phases for all baselines, point toward a jet that is off set by less than 0.5 mas from the continuum source and resolved in the direction of propagation, with a typical size of 2 mas. The jet position angle of similar to 80 degrees is consistent with the expected one at the observation date. Jet emission so close to the central binary system would suggest that line locking, if relevant to explain the amplitude and stability of the 0.26c jet velocity, operates on elements heavier than hydrogen. The Br gamma profile is broad and double peaked. It is better resolved than the continuum and the change of the phase signal sign across the line on all baselines suggests an East-West-oriented geometry similar to the jet direction and supporting a (polar) disk wind origin.

Published
2017

49. The inner rim of 51 HAeBe protoplanetary disks. A VLTI-Pionier survey

Author

Lazareff, B.

Abstract

We establish the following results: (a) Dust Tsub ~1800K. (b) Ring structure. (c) 1.65µm emission region is wide (Delta_r/r~0.5), favoring recent physical rim models. (d) Disk thickness z/h~0.2, larger than hydrostatic scaleheight (e) Extended (>>1AU) flux component; correlated with disk flaring indicators and group status. (f) Confirm and extend the size-luminosity relationship. (1) Authorship: B. Lazareff, J.-P. Berger , J. Kluska, J.-B. Le Bouquin, C. Pinte, W.-F. Thi, and 15 more co-authors.

Published
2016
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