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1. Four-of-a-kind? Comprehensive atmospheric characterisation of the HR 8799 planets with VLTI/GRAVITY

Author: Nasedkin, E., Mollière, P., Lacour, S., Nowak, M., Kreidberg, L., Stolker, T., Wang, J. J., Balmer, W. O., Kammerer, J., Shangguan, J., Abuter, R., Amorim, A., Asensio-Torres, R., Benisty, M., Berger, J. -P., Beust, H., Blunt, S., Boccaletti, A., Bonnefoy, M., Bonnet, H., Bordoni, M. S., Bourdarot, G., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Chavez, A., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., Davies, R., Dembet, R., Dexter, J., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Schreiber, N. M. Förster, Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Grant, S., Haubois, X., Heißel, G., Henning, Th., Hinkley, S., Hippler, S., Houllé, M., Hubert, Z., Jocou, L., Keppler, M., Kervella, P., Kurtovic, N. T., Lagrange, A. -M., Lapeyrère, V., Bouquin, J. -B. Le, Lutz, D., Maire, A. -L., Mang, F., Marleau, G. -D., Mérand, A., Monnier, J. D., Mordasini, C., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Pourré, N., Pueyo, L., Ribeiro, D. C., Rickman, E., Ruffio, J. B., Rustamkulov, Z., Shimizu, T., Sing, D., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Widmann, F., Winterhalder, T. O., Woillez, J., Yazici, S., Collaboration, the GRAVITY, Nasedkin, E., Mollière, P., Lacour, S., Nowak, M., Kreidberg, L., Stolker, T., Wang, J. J., Balmer, W. O., Kammerer, J., Shangguan, J., Abuter, R., Amorim, A., Asensio-Torres, R., Benisty, M., Berger, J. -P., Beust, H., Blunt, S., Boccaletti, A., Bonnefoy, M., Bonnet, H., Bordoni, M. S., Bourdarot, G., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Chavez, A., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., Davies, R., Dembet, R., Dexter, J., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Schreiber, N. M. Förster, Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Grant, S., Haubois, X., Heißel, G., Henning, Th., Hinkley, S., Hippler, S., Houllé, M., Hubert, Z., Jocou, L., Keppler, M., Kervella, P., Kurtovic, N. T., Lagrange, A. -M., Lapeyrère, V., Bouquin, J. -B. Le, Lutz, D., Maire, A. -L., Mang, F., Marleau, G. -D., Mérand, A., Monnier, J. D., Mordasini, C., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Pourré, N., Pueyo, L., Ribeiro, D. C., Rickman, E., Ruffio, J. B., Rustamkulov, Z., Shimizu, T., Sing, D., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Widmann, F., Winterhalder, T. O., Woillez, J., Yazici, S., and Collaboration, the GRAVITY
Abstract: With four companions at separations from 16 to 71 au, HR 8799 is a unique target for direct imaging, presenting an opportunity for the comparative study of exoplanets with a shared formation history. Combining new VLTI/GRAVITY observations obtained within the ExoGRAVITY program with archival data, we perform a systematic atmospheric characterisation of all four planets. We explore different levels of model flexibility to understand the temperature structure, chemistry and clouds of each planet using both petitRADTRANS atmospheric retrievals and fits to self-consistent radiative-convective equilibrium models. Using Bayesian Model Averaging to combine multiple retrievals, we find that the HR 8799 planets are highly enriched in metals, with [M/H] $\gtrsim$1, and have stellar to super-stellar C/O ratios. The C/O ratio increases with increasing separation from $0.55^{+0.12}_{-0.10}$ for d to $0.78^{+0.03}_{-0.04}$ for b, with the exception of the innermost planet which has a C/O ratio of $0.87\pm0.03$. By retrieving a quench pressure and using a disequilibrium chemistry model we derive vertical mixing strengths compatible with predictions for high-metallicity, self-luminous atmospheres. Bayesian evidence comparisons strongly favour the presence of HCN in HR 8799 c and e, as well as CH$_{4}$ in HR 8799 c, with detections at $>5\sigma$ confidence. All of the planets are cloudy, with no evidence for patchiness. The clouds of c, d and e are best fit by silicate clouds lying above a deep iron cloud layer, while the clouds of the cooler HR 8799 b are more likely composed of Na$_{2}$S. With well defined atmospheric properties, future exploration of this system is well positioned to unveil further detail in these planets, extending our understanding of the composition, structure, and formation history of these siblings., Comment: 45 pages, 25 figures, submitted to Astronomy & Astrophysics
Published: 2024

2. Combining Gaia and GRAVITY: Characterising Five New Directly Detected Substellar Companions

Author: Winterhalder, T. O., Lacour, S., Mérand, A., Maire, A. -L., Kammerer, J., Stolker, T., Pourré, N., Babusiaux, C., Abuter, R., Amorim, A., Asensio-Torres, R., Balmer, W. O., Benisty, M., Berger, J. -P., Beust, H., Blunt, S., Boccaletti, A., Bonnefoy, M., Bonnet, H., Bordoni, M. S., Bourdarot, G., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Chavez, A., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., Davies, R., Dembet, R., Dexter, J., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Schreiber, N. M. Förster, Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Grant, S., Haubois, X., Heißel, G., Henning, Th., Hinkley, S., Hippler, S., Houllé, M., Hubert, Z., Jocou, L., Keppler, M., Kervella, P., Kreidberg, L., Kurtovic, N. T., Lagrange, A. -M., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Lutz, D., Mang, F., Marleau, G. -D., Mollière, P., Monnier, J. D., Mordasini, C., Mouillet, D., Nasedkin, E., Nowak, M., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Pueyo, L., Ribeiro, D. C., Rickman, E., Rustamkulov, Z., Shangguan, J., Shimizu, T., Sing, D., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Wang, J. J., Widmann, F., Woillez, J., Yazıcı, Ş., Winterhalder, T. O., Lacour, S., Mérand, A., Maire, A. -L., Kammerer, J., Stolker, T., Pourré, N., Babusiaux, C., Abuter, R., Amorim, A., Asensio-Torres, R., Balmer, W. O., Benisty, M., Berger, J. -P., Beust, H., Blunt, S., Boccaletti, A., Bonnefoy, M., Bonnet, H., Bordoni, M. S., Bourdarot, G., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Chavez, A., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., Davies, R., Dembet, R., Dexter, J., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Schreiber, N. M. Förster, Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Grant, S., Haubois, X., Heißel, G., Henning, Th., Hinkley, S., Hippler, S., Houllé, M., Hubert, Z., Jocou, L., Keppler, M., Kervella, P., Kreidberg, L., Kurtovic, N. T., Lagrange, A. -M., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Lutz, D., Mang, F., Marleau, G. -D., Mollière, P., Monnier, J. D., Mordasini, C., Mouillet, D., Nasedkin, E., Nowak, M., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Pueyo, L., Ribeiro, D. C., Rickman, E., Rustamkulov, Z., Shangguan, J., Shimizu, T., Sing, D., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Wang, J. J., Widmann, F., Woillez, J., and Yazıcı, Ş.
Abstract: Precise mass constraints are vital for the characterisation of brown dwarfs and exoplanets. Here, we present how the combination of data obtained by Gaia and GRAVITY can help enlarge the sample of substellar companions with measured dynamical masses. We show how the Non-Single-Star (NSS) two-body orbit catalogue contained in Gaia DR3 can be used to inform high angular resolution follow-up observations with GRAVITY. Applying the method presented in this work for eight Gaia candidate systems, we detect all eight predicted companions, seven of which being previously unknown and five of substellar nature. Among the sample is Gaia DR3 2728129004119806464 B, which - detected at a angular separation of (34.01 $\pm$ 0.15) mas from the host - is the closest substellar companion ever imaged. In combination with the system's distance this translates to a physical separation of (1.054 $\pm$ 0.002) AU. The GRAVITY data are then used to break the host-companion mass degeneracy inherent to the Gaia NSS orbit solutions as well as to constrain the orbital solutions of the respective target systems. Knowledge of the companion masses enables us to further characterise them in terms of their age, effective temperature and radius by the application of evolutionary models. The results serve as an independent validation of the orbital solutions published in the NSS two-body orbit catalogue and show that the combination of astrometric survey missions and high-angular resolution direct imaging hold great promise for efficiently increasing the sample of directly-imaged companions in the future, especially in the light of the Gaia's upcoming DR4 and the advent of GRAVITY+., Comment: submitted to Astronomy and Astrophysics
Published: 2024

3. A catalogue of dual-field interferometric binary calibrators

Author: Nowak, M., Lacour, S., Abuter, R., Amorim, A., Asensio-Torres, R., Balmer, W. O., Benisty, M., Berger, J. -P., Beust, H., Blunt, S., Boccaletti, A., Bonnefoy, M., Bonnet, H., Bordoni, M. S., Bourdarot, G., Brandner, W., Cantalloube, F., Charnay, B., Chauvin, G., Chavez, A., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., Davies, R., Dembet, R., Dexter, J., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Schreiber, N. M. Förster, Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Grant, S., Haubois, X., Heißel, G., Henning, T., Hinkley, S., Hippler, S., Houllé, M., Hubert, Z., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Kreidberg, L., Kurtovic, N. T., Lagrange, A. -M., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Lutz, D., Maire, A. -L., Mang, F., Marleau, G. -D., Mérand, A., Monnier, J. D., Mordasini, C., Mouillet, D., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuh, O., Pourré, N., Pueyo, L., Ribeiro, D. C., Rickman, E., Rustamkulov, Z., Shangguan, J., Shimizu, T., Sing, D., Stadler, J., Stolker, T., Straub, O., Straubmeier, C., Sturm, E., Subroweit, M., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Wang, J. J., Widmann, F., Winterhalder, T. O., Woillez, J., Yazıcı, Ş., Young, A., Collaboration, the GRAVITY, Nowak, M., Lacour, S., Abuter, R., Amorim, A., Asensio-Torres, R., Balmer, W. O., Benisty, M., Berger, J. -P., Beust, H., Blunt, S., Boccaletti, A., Bonnefoy, M., Bonnet, H., Bordoni, M. S., Bourdarot, G., Brandner, W., Cantalloube, F., Charnay, B., Chauvin, G., Chavez, A., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., Davies, R., Dembet, R., Dexter, J., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Schreiber, N. M. Förster, Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Grant, S., Haubois, X., Heißel, G., Henning, T., Hinkley, S., Hippler, S., Houllé, M., Hubert, Z., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Kreidberg, L., Kurtovic, N. T., Lagrange, A. -M., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Lutz, D., Maire, A. -L., Mang, F., Marleau, G. -D., Mérand, A., Monnier, J. D., Mordasini, C., Mouillet, D., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuh, O., Pourré, N., Pueyo, L., Ribeiro, D. C., Rickman, E., Rustamkulov, Z., Shangguan, J., Shimizu, T., Sing, D., Stadler, J., Stolker, T., Straub, O., Straubmeier, C., Sturm, E., Subroweit, M., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Wang, J. J., Widmann, F., Winterhalder, T. O., Woillez, J., Yazıcı, Ş., Young, A., and Collaboration, the GRAVITY
Abstract: Dual-field interferometric observations with VLTI/GRAVITY sometimes require the use of a "binary calibrator", a binary star whose individual components remain unresolved by the interferometer, with a separation between 400 and 2000 mas for observations with the Units Telescopes (UTs), or 1200 to 3000 mas for the Auxiliary Telescopes (ATs). The separation vector also needs to be predictable to within 10 mas for proper pointing of the instrument. Up until now, no list of properly vetted calibrators was available for dual-field observations with VLTI/GRAVITY on the UTs. Our objective is to compile such a list, and make it available to the community. We identify a list of candidates from the Washington Double Star (WDS) catalogue, all with appropriate separations and brightness, scattered over the Southern sky. We observe them as part of a dedicated calibration programme, and determine whether these objects are true binaries (excluding higher multiplicities resolved interferometrically but unseen by imaging), and extract measurements of the separation vectors. We combine these new measurements with those available in the WDS to determine updated orbital parameters for all our vetted calibrators. We compile a list of 13 vetted binary calibrators for observations with VLTI/GRAVITY on the UTs, and provide orbital estimates and astrometric predictions for each of them. We show that our list guarantees that there are always at least two binary calibrators at airmass < 2 in the sky over the Paranal observatory, at any point in time. Any Principal Investigator wishing to use the dual-field mode of VLTI/GRAVITY with the UTs can now refer to this list to select an appropriate calibrator. We encourage the use of "whereistheplanet" to predict the astrometry of these calibrators, which seamlessly integrates with "p2Gravity" for VLTI/GRAVITY dual-field observing material preparation., Comment: 16 pages, 6 figures. Submitted to A&A
Published: 2024

4. Detecting life outside our solar system with a large high-contrast-imaging mission

Author: Snellen, Ignas A.G., Snik, F., Kenworthy, M., Albrecht, S., Anglada-Escudé, G., Baraffe, I., Baudoz, P., Benz, W., Beuzit, J. L., Biller, B., Birkby, J. L., Boccaletti, A., van Boekel, R., de Boer, J., Brogi, Matteo, Buchhave, L., Carone, L., Claire, M., Claudi, R., Demory, B. O., Désert, J. M., Desidera, S., Gaudi, B. S., Gratton, R., Gillon, M., Grenfell, J. L., Guyon, O., Henning, T., Hinkley, S., Huby, E., Janson, M., Helling, C., Heng, K., Kasper, M., Keller, C. U., Krause, O., Kreidberg, L., Madhusudhan, N., Lagrange, A. M., Launhardt, R., Lenton, T. M., Lopez-Puertas, M., Maire, A. L., Mayne, N., Meadows, V., Mennesson, B., Micela, G., Miguel, Y., Milli, J., Min, M., de Mooij, E., Mouillet, D., N’Diaye, M., D’Orazi, V., Palle, E., Pagano, I., Piotto, G., Queloz, D., Rauer, H., Ribas, I., Ruane, G., Selsis, F., Sozzetti, A., Stam, D., Stark, C. C., Vigan, A., de Visser, Pieter, Snellen, Ignas A.G., Snik, F., Kenworthy, M., Albrecht, S., Anglada-Escudé, G., Baraffe, I., Baudoz, P., Benz, W., Beuzit, J. L., Biller, B., Birkby, J. L., Boccaletti, A., van Boekel, R., de Boer, J., Brogi, Matteo, Buchhave, L., Carone, L., Claire, M., Claudi, R., Demory, B. O., Désert, J. M., Desidera, S., Gaudi, B. S., Gratton, R., Gillon, M., Grenfell, J. L., Guyon, O., Henning, T., Hinkley, S., Huby, E., Janson, M., Helling, C., Heng, K., Kasper, M., Keller, C. U., Krause, O., Kreidberg, L., Madhusudhan, N., Lagrange, A. M., Launhardt, R., Lenton, T. M., Lopez-Puertas, M., Maire, A. L., Mayne, N., Meadows, V., Mennesson, B., Micela, G., Miguel, Y., Milli, J., Min, M., de Mooij, E., Mouillet, D., N’Diaye, M., D’Orazi, V., Palle, E., Pagano, I., Piotto, G., Queloz, D., Rauer, H., Ribas, I., Ruane, G., Selsis, F., Sozzetti, A., Stam, D., Stark, C. C., Vigan, A., and de Visser, Pieter
Abstract: In this White Paper, which was submitted in response to the European Space Agency (ESA) Voyage 2050 Call, we recommend the ESA plays a proactive role in developing a global collaborative effort to construct a large high-contrast imaging space telescope, e.g. as currently under study by NASA. Such a mission will be needed to characterize a sizable sample of temperate Earth-like planets in the habitable zones of nearby Sun-like stars and to search for extraterrestrial biological activity. We provide an overview of relevant European expertise, and advocate ESA to start a technology development program towards detecting life outside the Solar System.
Published: 2023

5. First VLTI/GRAVITY Observations of HIP 65426 b: Evidence for a Low or Moderate Orbital Eccentricity

Author: Blunt, S., Balmer, W. O., Wang, J. J., Lacour, S., Petrus, S., Bourdarot, G., Kammerer, J., Pourré, N., Rickman, E., Shangguan, J., Winterhalder, T., Abuter, R., Amorim, A., Asensio-Torres, R., Benisty, M., Berger, J. -P., Beust, H., Boccaletti, A., Bohn, A., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Chavez, A., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., Dembet, R., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Feuchtgruber, H., Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Haubois, X., Heißel, G., Henning, Th., Hinkley, S., Hippler, S., Horrobin, M., Houllé, M., Hubert, Z., Jocou, L., Keppler, M., Kervella, P., Kreidberg, L., Lagrange, A. -M., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Lutz, D., Maire, A. -L., Mang, F., Marleau, G. -D., Mérand, A., Mollière, P., Monnier, J. D., Mordasini, C., Mouillet, D., Nasedkin, E., Nowak, M., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Pueyo, L., Rameau, J., Rodet, L., Rustamkulov, Z., Shimizu, T., Sing, D., Stolker, T., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., Young, A., Blunt, S., Balmer, W. O., Wang, J. J., Lacour, S., Petrus, S., Bourdarot, G., Kammerer, J., Pourré, N., Rickman, E., Shangguan, J., Winterhalder, T., Abuter, R., Amorim, A., Asensio-Torres, R., Benisty, M., Berger, J. -P., Beust, H., Boccaletti, A., Bohn, A., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Chavez, A., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., Dembet, R., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Feuchtgruber, H., Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Haubois, X., Heißel, G., Henning, Th., Hinkley, S., Hippler, S., Horrobin, M., Houllé, M., Hubert, Z., Jocou, L., Keppler, M., Kervella, P., Kreidberg, L., Lagrange, A. -M., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Lutz, D., Maire, A. -L., Mang, F., Marleau, G. -D., Mérand, A., Mollière, P., Monnier, J. D., Mordasini, C., Mouillet, D., Nasedkin, E., Nowak, M., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Pueyo, L., Rameau, J., Rodet, L., Rustamkulov, Z., Shimizu, T., Sing, D., Stolker, T., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., and Young, A.
Abstract: Giant exoplanets have been directly imaged over orders of magnitude of orbital separations, prompting theoretical and observational investigations of their formation pathways. In this paper, we present new VLTI/GRAVITY astrometric data of HIP 65426 b, a cold, giant exoplanet which is a particular challenge for most formation theories at a projected separation of 92 au from its primary. Leveraging GRAVITY's astrometric precision, we present an updated eccentricity posterior that disfavors large eccentricities. The eccentricity posterior is still prior-dependent, and we extensively interpret and discuss the limits of the posterior constraints presented here. We also perform updated spectral comparisons with self-consistent forward-modeled spectra, finding a best fit ExoREM model with solar metallicity and C/O=0.6. An important caveat is that it is difficult to estimate robust errors on these values, which are subject to interpolation errors as well as potentially missing model physics. Taken together, the orbital and atmospheric constraints paint a preliminary picture of formation inconsistent with scattering after disk dispersal. Further work is needed to validate this interpretation. Analysis code used to perform this work is available at https://github.com/sblunt/hip65426., Comment: 28 pages, 14 figures. Revised and resubmitted to AJ
Published: 2023

6. VLTI/GRAVITY Observations and Characterization of the Brown Dwarf Companion HD 72946 B

Author: Balmer, W. O., Pueyo, L., Stolker, T., Reggiani, H., Lacour, S., Maire, A. -L., Mollière, P., Nowak, M., Sing, D., Pourré, N., Blunt, S., Wang, J. J., Rickman, E., Henning, Th., Ward-Duong, K., Abuter, R., Amorim, A., Asensio-Torres, R., Benisty, M., Berger, J. -P., Beust, H., Boccaletti, A., Bohn, A., Bonnefoy, M., Bonnet, H., Bourdarot, G., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Chavez, A., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., Dembet, R., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Feuchtgruber, H., Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Haubois, X., Heißel, G., Hinkley, S., Hippler, S., Horrobin, M., Houllé, M., Hubert, Z., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Kreidberg, L., Lagrange, A. -M., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Lutz, D., Mang, F., Marleau, G. -D., Mérand, A., Monnier, J. D., Mordasini, C., Mouillet, D., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Rameau, J., Rodet, L., Rustamkulov, Z., Shangguan, J., Shimizu, T., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., Widmann, F., Wieprecht, E., Wiezorrek, E., Winterhalder, T., Woillez, J., Yazici, S., Young, A., Balmer, W. O., Pueyo, L., Stolker, T., Reggiani, H., Lacour, S., Maire, A. -L., Mollière, P., Nowak, M., Sing, D., Pourré, N., Blunt, S., Wang, J. J., Rickman, E., Henning, Th., Ward-Duong, K., Abuter, R., Amorim, A., Asensio-Torres, R., Benisty, M., Berger, J. -P., Beust, H., Boccaletti, A., Bohn, A., Bonnefoy, M., Bonnet, H., Bourdarot, G., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Chavez, A., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., Dembet, R., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Feuchtgruber, H., Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Haubois, X., Heißel, G., Hinkley, S., Hippler, S., Horrobin, M., Houllé, M., Hubert, Z., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Kreidberg, L., Lagrange, A. -M., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Lutz, D., Mang, F., Marleau, G. -D., Mérand, A., Monnier, J. D., Mordasini, C., Mouillet, D., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Rameau, J., Rodet, L., Rustamkulov, Z., Shangguan, J., Shimizu, T., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., Widmann, F., Wieprecht, E., Wiezorrek, E., Winterhalder, T., Woillez, J., Yazici, S., and Young, A.
Abstract: Tension remains between the observed and modeled properties of substellar objects, but objects in binary orbits, with known dynamical masses can provide a way forward. HD 72946 B is a recently imaged brown dwarf companion to the nearby, solar type star. We achieve $\sim100~\mu\mathrm{as}$ relative astrometry of HD 72946 B in the K-band using VLTI/GRAVITY, unprecedented for a benchmark brown dwarf. We fit an ensemble of measurements of the orbit using orbitize! and derive a strong dynamical mass constraint $\mathrm{M_B}=69.5\pm0.5~\mathrm{M_{Jup}}$ assuming a strong prior on the host star mass $\mathrm{M_A}=0.97\pm0.01~\mathrm{M_\odot}$ from an updated stellar analysis. We fit the spectrum of the companion to a grid of self-consistent BT-Settl-CIFIST model atmospheres, and perform atmospheric retrievals using petitRADTRANS. A dynamical mass prior only marginally influences the sampled distribution on effective temperature, but has a large influence on the surface gravity and radius, as expected. The dynamical mass alone does not strongly influence retrieved pressure-temperature or cloud parameters within our current retrieval setup. Independent of cloud prescription and prior assumptions, we find agreement within $\pm2\,\sigma$ between the C/O ratio of the host ($0.52\pm0.05)$ and brown dwarf ($0.43$ to $0.63$), as expected from a molecular cloud collapse formation scenario, but our retrieved metallicities are implausibly high ($0.6-0.8$) in light of an excellent agreement of the data with the solar abundance model grid. Future work on our retrieval framework will seek to resolve this tension. Additional study of low surface-gravity objects is necessary to assess the influence of a dynamical mass prior on atmospheric analysis., Comment: Accepted for publication in the Astrophysical Journal. 32 pages, 14 figures, 7 tables. v2&3 correct errors in co-author's affiliations, figure rendering, and some grant acknowledgements
Published: 2023
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7. VLTI/GRAVITY Provides Evidence the Young, Substellar Companion HD 136164 Ab formed like a 'Failed Star'

Author: Balmer, William O., Pueyo, L., Lacour, S., Wang, J. J., Stolker, T., Kammerer, J., Pourré, N., Nowak, M., Rickman, E., Blunt, S., Sivaramakrishnan, A., Sing, D., Wagner, K., Marleau, G. -D., Lagrange, A. -M., Abuter, R., Amorim, A., Asensio-Torres, R., Berger, J. -P., Beust, H., Boccaletti, A., Bohn, A., Bonnefoy, M., Bonnet, H., Bordoni, M. S., Bourdarot, G., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Chavez, A., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., Davies, R., Dembet, R., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Schreiber, N. M. F"orster, Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Grant, S., Haubois, X., Heißel, G., Henning, Th., Hinkley, S., Hippler, S., Houllé, M., Hubert, Z., Jocou, L., Keppler, M., Kervella, P., Kreidberg, L., Kurtovic, N. T., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Lutz, D., Maire, A. -L., Mang, F., Mérand, A., Mollière, P., Mordasini, C., Mouillet, D., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Ribeiro, D. C., Rodet, L., Rustamkulov, Z., Shangguan, J., Shimizu, T., Straubmeier, C., Sturm, E., Tacconi, L. J., Vigan, A., Vincent, F., Ward-Duong, K., Widmann, F., Winterhalder, T., Woillez, J., Yazici, S., Balmer, William O., Pueyo, L., Lacour, S., Wang, J. J., Stolker, T., Kammerer, J., Pourré, N., Nowak, M., Rickman, E., Blunt, S., Sivaramakrishnan, A., Sing, D., Wagner, K., Marleau, G. -D., Lagrange, A. -M., Abuter, R., Amorim, A., Asensio-Torres, R., Berger, J. -P., Beust, H., Boccaletti, A., Bohn, A., Bonnefoy, M., Bonnet, H., Bordoni, M. S., Bourdarot, G., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Chavez, A., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., Davies, R., Dembet, R., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Schreiber, N. M. F"orster, Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Grant, S., Haubois, X., Heißel, G., Henning, Th., Hinkley, S., Hippler, S., Houllé, M., Hubert, Z., Jocou, L., Keppler, M., Kervella, P., Kreidberg, L., Kurtovic, N. T., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Lutz, D., Maire, A. -L., Mang, F., Mérand, A., Mollière, P., Mordasini, C., Mouillet, D., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Ribeiro, D. C., Rodet, L., Rustamkulov, Z., Shangguan, J., Shimizu, T., Straubmeier, C., Sturm, E., Tacconi, L. J., Vigan, A., Vincent, F., Ward-Duong, K., Widmann, F., Winterhalder, T., Woillez, J., and Yazici, S.
Abstract: Young, low-mass Brown Dwarfs orbiting early-type stars, with low mass ratios ($q\lesssim0.01$), appear intrinsically rare and present a formation dilemma: could a handful of these objects be the highest mass outcomes of ``planetary" formation channels (bottom up within a protoplanetary disk), or are they more representative of the lowest mass ``failed binaries" (formed via disk fragmentation, or core fragmentation)? Additionally, their orbits can yield model-independent dynamical masses, and when paired with wide wavelength coverage and accurate system age estimates, can constrain evolutionary models in a regime where the models have a wide dispersion depending on initial conditions. We present new interferometric observations of the $16\,\mathrm{Myr}$ substellar companion HD~136164~Ab (HIP~75056~Ab) with VLTI/GRAVITY and an updated orbit fit including proper motion measurements from the Hipparcos-Gaia Catalogue of Accelerations. We estimate a dynamical mass of $35\pm10\,\mathrm{M_J}$ ($q\sim0.02$), making HD~136164~Ab the youngest substellar companion with a dynamical mass estimate. The new mass and newly constrained orbital eccentricity ($e=0.44\pm0.03$) and separation ($22.5\pm1\,\mathrm{au}$) could indicate that the companion formed via the low-mass tail of the Initial Mass Function. Our atmospheric fit to the \texttt{SPHINX} M-dwarf model grid suggests a sub-solar C/O ratio of $0.45$, and $3\times$ solar metallicity, which could indicate formation in the circumstellar disk via disk fragmentation. Either way, the revised mass estimate likely excludes ``bottom-up" formation via core accretion in the circumstellar disk. HD~136164~Ab joins a select group of young substellar objects with dynamical mass estimates; epoch astrometry from future \textit{Gaia} data releases will constrain the dynamical mass of this crucial object further., Comment: Accepted for publication in The Astronomical Journal. 9 figures, 3 tables
Published: 2023

8. Binary planet formation through tides

Author: Lazzoni, C., Rice, K. W., Zurlo, A., Hinkley, S., Desidera, S., Lazzoni, C., Rice, K. W., Zurlo, A., Hinkley, S., and Desidera, S.
Abstract: The search for satellites around exoplanets represents one of the greatest challenges in advancing the characterization of planetary systems. Currently, we can only detect massive satellites, which resemble additional planetary companions rather than rocky moons. It is not yet well understood whether such substellar pairs, known as binary planets, are common or how they form. In this study, we investigated the formation scenario for binary planets resulting from tidal dissipation during close encounters in the gravitational instability scenario. We conducted seven sets of simulations, varying the number of initial planets injected into the system from two to five, as well as the amount of energy lost due to tides. Our results demonstrate that this formation mechanism is quite efficient in producing binary planets, with an average occurrence rate for the simulated systems of 14.3%. Additionally, we present the distribution of relevant physical parameters (semi-major axis, eccentricity, mass ratios, and formation time) for planet-planet pairs. We also provide comprehensive statistics for single planets and planet-planet pairs., Comment: 11 pages, 12 figures
Published: 2023

9. Direct discovery of the inner exoplanet in the HD206893 system. Evidence for deuterium burning in a planetary-mass companion

Author: Hinkley, S., Lacour, S., Marleau, G. -D., Lagrange, A. M., Wang, J. J., Kammerer, J., Cumming, A., Nowak, M., Rodet, L., Stolker, T., Balmer, W. -O., Ray, S., Bonnefoy, M., Mollière, P., Lazzoni, C., Kennedy, G., Mordasini, C., Abuter, R., Aigrain, S., Amorim, A., Asensio-Torres, R., Babusiaux, C., Benisty, M., Berger, J. -P., Beust, H., Blunt, S., Boccaletti, A., Bohn, A., Bonnet, H., Bourdarot, G., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Chomez, A., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., Delorme, P., Dembet, R., de Zeeuw, P. T., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Feuchtgruber, H., Galland, F., Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Grandjean, A., Haubois, X., Heißel, G., Henning, Th., Hippler, S., Horrobin, M., Houllé, M., Hubert, Z., Jocou, L., Keppler, M., Kervella, P., Kreidberg, L., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Lutz, D., Maire, A. -L., Mang, F., Mérand, A., Meunier, N., Monnier, J. D., Mouillet, D., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Philipot, F., Pfuhl, O., Pourré, N., Pueyo, L., Rameau, J., Rickman, E., Rubini, P., Rustamkulov, Z., Samland, M., Shangguan, J., Shimizu, T., Sing, D., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., Young, A., Zicher, N., Collaboration, the GRAVITY, Hinkley, S., Lacour, S., Marleau, G. -D., Lagrange, A. M., Wang, J. J., Kammerer, J., Cumming, A., Nowak, M., Rodet, L., Stolker, T., Balmer, W. -O., Ray, S., Bonnefoy, M., Mollière, P., Lazzoni, C., Kennedy, G., Mordasini, C., Abuter, R., Aigrain, S., Amorim, A., Asensio-Torres, R., Babusiaux, C., Benisty, M., Berger, J. -P., Beust, H., Blunt, S., Boccaletti, A., Bohn, A., Bonnet, H., Bourdarot, G., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Chomez, A., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., Delorme, P., Dembet, R., de Zeeuw, P. T., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Feuchtgruber, H., Galland, F., Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Grandjean, A., Haubois, X., Heißel, G., Henning, Th., Hippler, S., Horrobin, M., Houllé, M., Hubert, Z., Jocou, L., Keppler, M., Kervella, P., Kreidberg, L., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Lutz, D., Maire, A. -L., Mang, F., Mérand, A., Meunier, N., Monnier, J. D., Mouillet, D., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Philipot, F., Pfuhl, O., Pourré, N., Pueyo, L., Rameau, J., Rickman, E., Rubini, P., Rustamkulov, Z., Samland, M., Shangguan, J., Shimizu, T., Sing, D., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., Young, A., Zicher, N., and Collaboration, the GRAVITY
Abstract: Long term precise radial velocity (RV) monitoring of the nearby star HD206893, as well as anomalies in the system proper motion, have suggested the presence of an additional, inner companion in the system. Here we describe the results of a multi-epoch search for the companion responsible for this RV drift and proper motion anomaly using the VLTI/GRAVITY instrument. Utilizing information from ongoing precision RV measurements with the HARPS spectrograph, as well as Gaia host star astrometry, we report a high significance detection of the companion HD206893c over three epochs, with clear evidence for Keplerian orbital motion. Our astrometry with $\sim$50-100 $\mu$arcsec precision afforded by GRAVITY allows us to derive a dynamical mass of 12.7$^{+1.2}_{-1.0}$ M$_{\rm Jup}$ and an orbital separation of 3.53$^{+0.08}_{-0.06}$ au for HD206893c. Our fits to the orbits of both companions in the system utilize both Gaia astrometry and RVs to also provide a precise dynamical estimate of the previously uncertain mass of the B component, and therefore derive an age of $155\pm15$ Myr. We find that theoretical atmospheric/evolutionary models incorporating deuterium burning for HD206893c, parameterized by cloudy atmospheres provide a good simultaneous fit to the luminosity of both HD206893B and c. In addition to utilizing long-term RV information, this effort is an early example of a direct imaging discovery of a bona fide exoplanet that was guided in part with Gaia astrometry. Utilizing Gaia astrometry is expected to be one of the primary techniques going forward to identify and characterize additional directly imaged planets. Lastly, this discovery is another example of the power of optical interferometry to directly detect and characterize extrasolar planets where they form at ice-line orbital separations of 2-4\,au., Comment: Accepted to A&A
Published: 2022
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10. Narrow belt of debris around the Sco-Cen star HD 141011

Author: Bonnefoy, M., Milli, J., Menard, F., Delorme, P., Chomez, A., Bonavita, M., Lagrange, A-M., Vigan, A., Augereau, J. C., Beuzit, J. L., Biller, B., Boccaletti, A., Chauvin, G., Desidera, S., Faramaz, V., Galicher, R., Gratton, R., Hinkley, S., Lazzoni, C., Matthews, E., Mesa, D., Mordasini, C., Mouillet, D., Olofsson, J., Pinte, C., Bonnefoy, M., Milli, J., Menard, F., Delorme, P., Chomez, A., Bonavita, M., Lagrange, A-M., Vigan, A., Augereau, J. C., Beuzit, J. L., Biller, B., Boccaletti, A., Chauvin, G., Desidera, S., Faramaz, V., Galicher, R., Gratton, R., Hinkley, S., Lazzoni, C., Matthews, E., Mesa, D., Mordasini, C., Mouillet, D., Olofsson, J., and Pinte, C.
Abstract: We initiated a deep-imaging survey of Scorpius-Centaurus A-F stars with predicted warm inner and cold outer belts of debris reminiscent of the architecture of emblematic systems such as HR 8799. We present resolved SPHERE images of a narrow ring of debris around the F5-type star HD 141011 that was observed as part of our survey in 2015, 2016, and 2019. The ring extends up to ~1.1" (~141 au) from the star in the IRDIS and IFS data obtained in 2016 and 2019. The disk is not detected in the 2015 data which are of poorer quality. The disks is best reproduced by models of a noneccentric ring centered on the star with an inclination of $69.1\pm0.9^{\circ}$, a position angle of $-24.6 \pm 1.7^{\circ}$, and a semimajor axis of $127.5\pm3.8$ au. The combination of radial velocity and imaging data excludes brown-dwarf (M>13.6 MJup) companions coplanar with the disk from 0.1 to 0.9 au and from 20 au up to 500 au (90% probability). HD 141011 adds to the growing list of debris disks that are resolved in Sco-Cen. It is one of the faintest disks that are resolved from the ground and has a radial extent and fractional width ($\sim$12.5%) reminiscent of Fomalhaut. Its moderate inclination and large semimajor axis make it a good target for the James Webb Space Telescope and should allow a deeper search for putative companions shaping the dust distribution., Comment: 13 pages, 10 figures. Paper II of our Sco-Cen imaging survey. Accepted in A&A
Published: 2021
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11. The mass of Beta Pictoris c from Beta Pictoris b orbital motion

Author: Lacour, S., Wang, J. J., Rodet, L., Nowak, M., Shangguan, J., Beust, H., Lagrange, A. -M., Abuter, R., Amorim, A., Asensio-Torres, R., Benisty, M., Berger, J. -P., Blunt, S., Boccaletti, A., Bohn, A., Bolzer, M. -L., Bonnefoy, M., Bonnet, H., Bourdarot, G., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., Dembet, R., Dexter, J., de Zeeuw, P. T., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Haubois, X., Heißel, G., Henning, Th., Hinkley, S., Hippler, S., Horrobin, M., Houllé, M., Hubert, Z., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Kreidberg, L., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Lutz, D., Maire, A. -L., Mérand, A., Mollière, P., Monnier, J. D., Mouillet, D., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Rickman, E., Pueyo, L., Rameau, J., Rousset, G., Rustamkulov, Z., Samland, M., Shimizu, T., Sing, D., Stadler, J., Stolker, T., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., Young, A., Collaboration, the GRAVITY, Lacour, S., Wang, J. J., Rodet, L., Nowak, M., Shangguan, J., Beust, H., Lagrange, A. -M., Abuter, R., Amorim, A., Asensio-Torres, R., Benisty, M., Berger, J. -P., Blunt, S., Boccaletti, A., Bohn, A., Bolzer, M. -L., Bonnefoy, M., Bonnet, H., Bourdarot, G., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., Dembet, R., Dexter, J., de Zeeuw, P. T., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Haubois, X., Heißel, G., Henning, Th., Hinkley, S., Hippler, S., Horrobin, M., Houllé, M., Hubert, Z., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Kreidberg, L., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Lutz, D., Maire, A. -L., Mérand, A., Mollière, P., Monnier, J. D., Mouillet, D., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Rickman, E., Pueyo, L., Rameau, J., Rousset, G., Rustamkulov, Z., Samland, M., Shimizu, T., Sing, D., Stadler, J., Stolker, T., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., Young, A., and Collaboration, the GRAVITY
Abstract: We aim to demonstrate that the presence and mass of an exoplanet can now be effectively derived from the astrometry of another exoplanet. We combined previous astrometry of $\beta$ Pictoris b with a new set of observations from the GRAVITY interferometer. The orbital motion of $\beta$ Pictoris b is fit using Markov chain Monte Carlo simulations in Jacobi coordinates. The inner planet, $\beta$ Pictoris c, was also reobserved at a separation of 96\,mas, confirming the previous orbital estimations. From the astrometry of planet b only, we can (i) detect the presence of $\beta$ Pictoris c and (ii) constrain its mass to $10.04^{+4.53}_{-3.10}\,M_{\rm Jup}$. If one adds the astrometry of $\beta$ Pictoris c, the mass is narrowed down to $9.15^{+1.08}_{-1.06}\,M_{\rm Jup}$. The inclusion of radial velocity measurements does not affect the orbital parameters significantly, but it does slightly decrease the mass estimate to $8.89^{+0.75}_{-0.75}\,M_{\rm Jup}$. With a semimajor axis of $2.68\pm0.02$\,au, a period of $1221\pm15$ days, and an eccentricity of $0.32\pm0.02$, the orbital parameters of $\beta$ Pictoris c are now constrained as precisely as those of $\beta$ Pictoris b. The orbital configuration is compatible with a high-order mean-motion resonance (7:1). The impact of the resonance on the planets' dynamics would then be negligible with respect to the secular perturbations, which might have played an important role in the eccentricity excitation of the outer planet., Comment: Accepted in A&A Letter
Published: 2021
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12. GRAVITY K-band spectroscopy of HD 206893 B: brown dwarf or exoplanet

Author: Kammerer, J., Lacour, S., Stolker, T., Mollière, P., Sing, D. K., Nasedkin, E., Kervella, P., Wang, J. J., Ward-Duong, K., Nowak, M., Abuter, R., Amorim, A., Asensio-Torres, R., Bauböck, M., Benisty, M., Berger, J. -P., Beust, H., Blunt, S., Boccaletti, A., Bohn, A., Bolzer, M. -L., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., Dembet, R., Dexter, J., de Zeeuw, P. T., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Girard, J., Haubois, X., Heißel, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houllé, M., Hubert, Z., Jocou, L., Keppler, M., Kreidberg, L., Lagrange, A. -M., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Lutz, D., Maire, A. -L., Mérand, A., Monnier, J. D., Mouillet, D., Müller, A., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Pueyo, L., Rameau, J., Rodet, L., Rousset, G., Rustamkulov, Z., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., Collaboration, GRAVITY, Kammerer, J., Lacour, S., Stolker, T., Mollière, P., Sing, D. K., Nasedkin, E., Kervella, P., Wang, J. J., Ward-Duong, K., Nowak, M., Abuter, R., Amorim, A., Asensio-Torres, R., Bauböck, M., Benisty, M., Berger, J. -P., Beust, H., Blunt, S., Boccaletti, A., Bohn, A., Bolzer, M. -L., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., Dembet, R., Dexter, J., de Zeeuw, P. T., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Girard, J., Haubois, X., Heißel, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houllé, M., Hubert, Z., Jocou, L., Keppler, M., Kreidberg, L., Lagrange, A. -M., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Lutz, D., Maire, A. -L., Mérand, A., Monnier, J. D., Mouillet, D., Müller, A., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Pueyo, L., Rameau, J., Rodet, L., Rousset, G., Rustamkulov, Z., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., and Collaboration, GRAVITY
Abstract: We aim to reveal the nature of the reddest known substellar companion HD 206893 B by studying its near-infrared colors and spectral morphology and by investigating its orbital motion. We fit atmospheric models for giant planets and brown dwarfs and perform spectral retrievals with petitRADTRANS and ATMO on the observed GRAVITY, SPHERE, and GPI spectra of HD 206893 B. To recover its unusual spectral features, we include additional extinction by high-altitude dust clouds made of enstatite grains in the atmospheric model fits. We also infer the orbital parameters of HD 206893 B by combining the $\sim 100~\mu\text{as}$ precision astrometry from GRAVITY with data from the literature and constrain the mass and position of HD 206893 C based on the Gaia proper motion anomaly of the system. The extremely red color and the very shallow $1.4~\mu\text{m}$ water absorption feature of HD 206893 B can be fit well with the adapted atmospheric models and spectral retrievals. Altogether, our analysis suggests an age of $\sim 3$-$300~\text{Myr}$ and a mass of $\sim 5$-$30~\text{M}_\text{Jup}$ for HD 206893 B, which is consistent with previous estimates but extends the parameter space to younger and lower-mass objects. The GRAVITY astrometry points to an eccentric orbit ($e = 0.29^{+0.06}_{-0.11}$) with a mutual inclination of $< 34.4~\text{deg}$ with respect to the debris disk of the system. While HD 206893 B could in principle be a planetary-mass companion, this possibility hinges on the unknown influence of the inner companion on the mass estimate of $10^{+5}_{-4}~\text{M}_\text{Jup}$ from radial velocity and Gaia as well as a relatively small but significant Argus moving group membership probability of $\sim 61\%$. However, we find that if the mass of HD 206893 B is $< 30~\text{M}_\text{Jup}$, then the inner companion HD 206893 C should have a mass between $\sim 8$-$15~\text{M}_\text{Jup}$., Comment: 28 pages, 19 figures, accepted for publication in A&A
Published: 2021
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13. Constraining the Nature of the PDS 70 Protoplanets with VLTI/GRAVITY*

Author: Wang, J. J., Vigan, A., Lacour, S., Nowak, M., Stolker, T., De Rosa, R. J., Ginzburg, S., Gao, P., Abuter, R., Amorim, A., Asensio-Torres, R., Bauboeck, M., Benisty, M., Berger, J. P., Beust, H., Beuzit, J. -L., Blunt, S., Boccaletti, A., Bohn, A., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V., Clenet, Y., du Foresto, V. Coude, Cridland, A., Zeeuw, P. T. de, Dembet, R., Dexter, J., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Facchini, S., Gao, F., Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J., Haubois, X., Heissel, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houlle, M., Hubert, Z., Jimenez-Rosales, A., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Meyer, M., Kreidberg, L., Lagrange, A. -M., Lapeyrere, V., Bouquin, J. -B. Le, Lena, P., Lutz, D., Maire, A. -L., Menard, F., Merand, A., Molliere, P., Monnier, J. D., Mouillet, D., Mueller, A., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Pueyo, L., Rameau, J., Rodet, L., Rodriguez-Coira, G., Rousset, G., Scheithauer, S., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., Dishoeck, E. F. van, Vincent, F., Fellenberg, S. D. von, Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Wang, J. J., Vigan, A., Lacour, S., Nowak, M., Stolker, T., De Rosa, R. J., Ginzburg, S., Gao, P., Abuter, R., Amorim, A., Asensio-Torres, R., Bauboeck, M., Benisty, M., Berger, J. P., Beust, H., Beuzit, J. -L., Blunt, S., Boccaletti, A., Bohn, A., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V., Clenet, Y., du Foresto, V. Coude, Cridland, A., Zeeuw, P. T. de, Dembet, R., Dexter, J., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Facchini, S., Gao, F., Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J., Haubois, X., Heissel, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houlle, M., Hubert, Z., Jimenez-Rosales, A., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Meyer, M., Kreidberg, L., Lagrange, A. -M., Lapeyrere, V., Bouquin, J. -B. Le, Lena, P., Lutz, D., Maire, A. -L., Menard, F., Merand, A., Molliere, P., Monnier, J. D., Mouillet, D., Mueller, A., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Pueyo, L., Rameau, J., Rodet, L., Rodriguez-Coira, G., Rousset, G., Scheithauer, S., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., Dishoeck, E. F. van, Vincent, F., Fellenberg, S. D. von, Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., and Woillez, J.
Abstract: We present K-band interferometric observations of the PDS 70 protoplanets along with their host star using VLTI/GRAVITY. We obtained K-band spectra and 100 mu as precision astrometry of both PDS 70 b and c in two epochs, as well as spatially resolving the hot inner disk around the star. Rejecting unstable orbits, we found a nonzero eccentricity for PDS 70 b of 0.17 0.06, a near-circular orbit for PDS 70 c, and an orbital configuration that is consistent with the planets migrating into a 2:1 mean motion resonance. Enforcing dynamical stability, we obtained a 95% upper limit on the mass of PDS 70 b of 10 M-Jup, while the mass of PDS 70 c was unconstrained. The GRAVITY K-band spectra rules out pure blackbody models for the photospheres of both planets. Instead, the models with the most support from the data are planetary atmospheres that are dusty, but the nature of the dust is unclear. Any circumplanetary dust around these planets is not well constrained by the planets' 1-5 mu m spectral energy distributions (SEDs) and requires longer wavelength data to probe with SED analysis. However with VLTI/GRAVITY, we made the first observations of a circumplanetary environment with sub-astronomical-unit spatial resolution, placing an upper limit of 0.3 au on the size of a bright disk around PDS 70 b.
Published: 2021

14. The mass of beta Pictoris c from beta Pictoris b orbital motion

Author: Lacour, S., Wang, J. J., Rodet, L., Nowak, M., Shangguan, J., Beust, H., Lagrange, A-M, Abuter, R., Amorim, A., Asensio-Torres, R., Benisty, M., Berger, J-P, Blunt, S., Boccaletti, A., Bohn, A., Bolzer, M-L, Bonnefoy, M., Bonnet, H., Bourdarot, G., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V, Clenet, Y., du Foresto, V. Coude, Cridland, A., Dembet, R., Dexter, J., de Zeeuw, T., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Haubois, X., Heissel, G., Henning, Th, Hinkley, S., Hippler, S., Horrobin, M., Houlle, M., Hubert, Z., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Kreidberg, L., Lapeyrere, V, Le Bouquin, J-B, Lena, P., Lutz, D., Maire, A-L, Merand, A., Molliere, P., Monnier, J. D., Mouillet, D., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Rickman, E., Pueyo, L., Rameau, J., Rousset, G., Rustamkulov, Z., Samland, M., Shimizu, T., Sing, D., Stadler, J., Stolker, T., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., Young, A., Lacour, S., Wang, J. J., Rodet, L., Nowak, M., Shangguan, J., Beust, H., Lagrange, A-M, Abuter, R., Amorim, A., Asensio-Torres, R., Benisty, M., Berger, J-P, Blunt, S., Boccaletti, A., Bohn, A., Bolzer, M-L, Bonnefoy, M., Bonnet, H., Bourdarot, G., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V, Clenet, Y., du Foresto, V. Coude, Cridland, A., Dembet, R., Dexter, J., de Zeeuw, T., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Haubois, X., Heissel, G., Henning, Th, Hinkley, S., Hippler, S., Horrobin, M., Houlle, M., Hubert, Z., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Kreidberg, L., Lapeyrere, V, Le Bouquin, J-B, Lena, P., Lutz, D., Maire, A-L, Merand, A., Molliere, P., Monnier, J. D., Mouillet, D., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Rickman, E., Pueyo, L., Rameau, J., Rousset, G., Rustamkulov, Z., Samland, M., Shimizu, T., Sing, D., Stadler, J., Stolker, T., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., and Young, A.
Abstract: Aims. We aim to demonstrate that the presence and mass of an exoplanet can now be effectively derived from the astrometry of another exoplanet. Methods. We combined previous astrometry of beta Pictoris b with a new set of observations from the GRAVITY interferometer. The orbital motion of beta Pictoris b is fit using Markov chain Monte Carlo simulations in Jacobi coordinates. The inner planet, beta Pictoris c, was also reobserved at a separation of 96 mas, confirming the previous orbital estimations. Results. From the astrometry of planet b only, we can (i) detect the presence of beta Pictoris c and (ii) constrain its mass to 10.04(-3.10)(+4.53) M-Jup . If one adds the astrometry of beta Pictoris c, the mass is narrowed down to 9.15(-1.06)(+1.08) M-Jup. The inclusion of radial velocity measurements does not affect the orbital parameters significantly, but it does slightly decrease the mass estimate to 8.89(-0.75)(+0.75) M-Jup.With a semimajor axis of 2.68 +/- 0.02 au, a period of 1221 +/- 15 days, and an eccentricity of 0.32 +/- 0.02, the orbital parameters of beta Pictoris c are now constrained as precisely as those of beta Pictoris b. The orbital configuration is compatible with a high-order mean-motion resonance (7:1). The impact of the resonance on the planets' dynamics would then be negligible with respect to the secular perturbations, which might have played an important role in the eccentricity excitation of the outer planet.
Published: 2021

15. GRAVITY K-band spectroscopy of HD 206893 B Brown dwarf or exoplanet

Author: Kammerer, J., Lacour, S., Stolker, T., Molliere, P., Sing, D. K., Nasedkin, E., Kervella, P., Wang, J. J., Ward-Duong, K., Nowak, M., Abuter, R., Amorim, A., Asensio-Torres, R., Baubock, M., Benisty, M., Berger, J-P, Beust, H., Blunt, S., Boccaletti, A., Bohn, A., Bolzer, M-L, Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V, Clenet, Y., du Foresto, V. Coude, Cridland, A., Dembet, R., Dexter, J., de Zeeuw, P. T., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Girard, J., Haubois, X., Heissel, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houlle, M., Hubert, Z., Jocou, L., Keppler, M., Kreidberg, L., Lagrange, A-M, Lapeyrere, V, Le Bouquin, J-B, Lena, P., Lutz, D., Maire, A-L, Merand, A., Monnier, J. D., Mouillet, D., Muller, A., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Pueyo, L., Rameau, J., Rodet, L., Rousset, G., Rustamkulov, Z., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., Kammerer, J., Lacour, S., Stolker, T., Molliere, P., Sing, D. K., Nasedkin, E., Kervella, P., Wang, J. J., Ward-Duong, K., Nowak, M., Abuter, R., Amorim, A., Asensio-Torres, R., Baubock, M., Benisty, M., Berger, J-P, Beust, H., Blunt, S., Boccaletti, A., Bohn, A., Bolzer, M-L, Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V, Clenet, Y., du Foresto, V. Coude, Cridland, A., Dembet, R., Dexter, J., de Zeeuw, P. T., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Girard, J., Haubois, X., Heissel, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houlle, M., Hubert, Z., Jocou, L., Keppler, M., Kreidberg, L., Lagrange, A-M, Lapeyrere, V, Le Bouquin, J-B, Lena, P., Lutz, D., Maire, A-L, Merand, A., Monnier, J. D., Mouillet, D., Muller, A., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Pueyo, L., Rameau, J., Rodet, L., Rousset, G., Rustamkulov, Z., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., and Yazici, S.
Abstract: Context. Near-infrared interferometry has become a powerful tool for studying the orbital and atmospheric parameters of substellar companions. Aims. We aim to reveal the nature of the reddest known substellar companion HD 206893 B by studying its near-infrared colors and spectral morphology and by investigating its orbital motion. Methods. We fit atmospheric models for giant planets and brown dwarfs and perform spectral retrievals with petitRADTRANS and ATMO on the observed GRAVITY, SPHERE, and GPI spectra of HD 206893 B. To recover its unusual spectral features, first and foremost its extremely red near-infrared color, we include additional extinction by high-altitude dust clouds made of enstatite grains in the atmospheric model fits. However, forsterite, corundum, and iron grains predict similar extinction curves for the grain sizes considered here. We also infer the orbital parameters of HD 206893 B by combining the similar to 100 mu as precision astrometry from GRAVITY with data from the literature and constrain the mass and position of HD 206893 C based on the Gaia proper motion anomaly of the system. Results. The extremely red color and the very shallow 1.4 mu m water absorption feature of HD 206893 B can be fit well with the adapted atmospheric models and spectral retrievals. By comparison with AMES-Cond evolutionary tracks, we find that only some atmosphericmodels predict physically plausible objects. Altogether, our analysis suggests an age of similar to 3-300 Myr and a mass of similar to 5-30 M-Jup for HD 206893 B, which is consistent with previous estimates but extends the parameter space to younger and lower-mass objects. The GRAVITY astrometry points to an eccentric orbit (e = 0.29(-0.11)(+0.06)) with a mutual inclination of <34.4 deg with respect to the debris disk of the system. Conclusions. While HD 206893 B could in principle be a planetary-mass companion, this possibility hinges on the unknown influence of the inner companion on the mass estimate o
Published: 2021

16. GRAVITY K-band spectroscopy of HD 206893 B Brown dwarf or exoplanet

Author: Kammerer, J., Lacour, S., Stolker, T., Molliere, P., Sing, D. K., Nasedkin, E., Kervella, P., Wang, J. J., Ward-Duong, K., Nowak, M., Abuter, R., Amorim, A., Asensio-Torres, R., Baubock, M., Benisty, M., Berger, J-P, Beust, H., Blunt, S., Boccaletti, A., Bohn, A., Bolzer, M-L, Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V, Clenet, Y., du Foresto, V. Coude, Cridland, A., Dembet, R., Dexter, J., de Zeeuw, P. T., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Girard, J., Haubois, X., Heissel, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houlle, M., Hubert, Z., Jocou, L., Keppler, M., Kreidberg, L., Lagrange, A-M, Lapeyrere, V, Le Bouquin, J-B, Lena, P., Lutz, D., Maire, A-L, Merand, A., Monnier, J. D., Mouillet, D., Muller, A., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Pueyo, L., Rameau, J., Rodet, L., Rousset, G., Rustamkulov, Z., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., Kammerer, J., Lacour, S., Stolker, T., Molliere, P., Sing, D. K., Nasedkin, E., Kervella, P., Wang, J. J., Ward-Duong, K., Nowak, M., Abuter, R., Amorim, A., Asensio-Torres, R., Baubock, M., Benisty, M., Berger, J-P, Beust, H., Blunt, S., Boccaletti, A., Bohn, A., Bolzer, M-L, Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V, Clenet, Y., du Foresto, V. Coude, Cridland, A., Dembet, R., Dexter, J., de Zeeuw, P. T., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Girard, J., Haubois, X., Heissel, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houlle, M., Hubert, Z., Jocou, L., Keppler, M., Kreidberg, L., Lagrange, A-M, Lapeyrere, V, Le Bouquin, J-B, Lena, P., Lutz, D., Maire, A-L, Merand, A., Monnier, J. D., Mouillet, D., Muller, A., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Pueyo, L., Rameau, J., Rodet, L., Rousset, G., Rustamkulov, Z., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., and Yazici, S.
Abstract: Context. Near-infrared interferometry has become a powerful tool for studying the orbital and atmospheric parameters of substellar companions. Aims. We aim to reveal the nature of the reddest known substellar companion HD 206893 B by studying its near-infrared colors and spectral morphology and by investigating its orbital motion. Methods. We fit atmospheric models for giant planets and brown dwarfs and perform spectral retrievals with petitRADTRANS and ATMO on the observed GRAVITY, SPHERE, and GPI spectra of HD 206893 B. To recover its unusual spectral features, first and foremost its extremely red near-infrared color, we include additional extinction by high-altitude dust clouds made of enstatite grains in the atmospheric model fits. However, forsterite, corundum, and iron grains predict similar extinction curves for the grain sizes considered here. We also infer the orbital parameters of HD 206893 B by combining the similar to 100 mu as precision astrometry from GRAVITY with data from the literature and constrain the mass and position of HD 206893 C based on the Gaia proper motion anomaly of the system. Results. The extremely red color and the very shallow 1.4 mu m water absorption feature of HD 206893 B can be fit well with the adapted atmospheric models and spectral retrievals. By comparison with AMES-Cond evolutionary tracks, we find that only some atmosphericmodels predict physically plausible objects. Altogether, our analysis suggests an age of similar to 3-300 Myr and a mass of similar to 5-30 M-Jup for HD 206893 B, which is consistent with previous estimates but extends the parameter space to younger and lower-mass objects. The GRAVITY astrometry points to an eccentric orbit (e = 0.29(-0.11)(+0.06)) with a mutual inclination of <34.4 deg with respect to the debris disk of the system. Conclusions. While HD 206893 B could in principle be a planetary-mass companion, this possibility hinges on the unknown influence of the inner companion on the mass estimate o
Published: 2021

17. The mass of beta Pictoris c from beta Pictoris b orbital motion

Author: Lacour, S., Wang, J. J., Rodet, L., Nowak, M., Shangguan, J., Beust, H., Lagrange, A-M, Abuter, R., Amorim, A., Asensio-Torres, R., Benisty, M., Berger, J-P, Blunt, S., Boccaletti, A., Bohn, A., Bolzer, M-L, Bonnefoy, M., Bonnet, H., Bourdarot, G., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V, Clenet, Y., du Foresto, V. Coude, Cridland, A., Dembet, R., Dexter, J., de Zeeuw, T., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Haubois, X., Heissel, G., Henning, Th, Hinkley, S., Hippler, S., Horrobin, M., Houlle, M., Hubert, Z., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Kreidberg, L., Lapeyrere, V, Le Bouquin, J-B, Lena, P., Lutz, D., Maire, A-L, Merand, A., Molliere, P., Monnier, J. D., Mouillet, D., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Rickman, E., Pueyo, L., Rameau, J., Rousset, G., Rustamkulov, Z., Samland, M., Shimizu, T., Sing, D., Stadler, J., Stolker, T., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., Young, A., Lacour, S., Wang, J. J., Rodet, L., Nowak, M., Shangguan, J., Beust, H., Lagrange, A-M, Abuter, R., Amorim, A., Asensio-Torres, R., Benisty, M., Berger, J-P, Blunt, S., Boccaletti, A., Bohn, A., Bolzer, M-L, Bonnefoy, M., Bonnet, H., Bourdarot, G., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V, Clenet, Y., du Foresto, V. Coude, Cridland, A., Dembet, R., Dexter, J., de Zeeuw, T., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Haubois, X., Heissel, G., Henning, Th, Hinkley, S., Hippler, S., Horrobin, M., Houlle, M., Hubert, Z., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Kreidberg, L., Lapeyrere, V, Le Bouquin, J-B, Lena, P., Lutz, D., Maire, A-L, Merand, A., Molliere, P., Monnier, J. D., Mouillet, D., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Rickman, E., Pueyo, L., Rameau, J., Rousset, G., Rustamkulov, Z., Samland, M., Shimizu, T., Sing, D., Stadler, J., Stolker, T., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., and Young, A.
Abstract: Aims. We aim to demonstrate that the presence and mass of an exoplanet can now be effectively derived from the astrometry of another exoplanet. Methods. We combined previous astrometry of beta Pictoris b with a new set of observations from the GRAVITY interferometer. The orbital motion of beta Pictoris b is fit using Markov chain Monte Carlo simulations in Jacobi coordinates. The inner planet, beta Pictoris c, was also reobserved at a separation of 96 mas, confirming the previous orbital estimations. Results. From the astrometry of planet b only, we can (i) detect the presence of beta Pictoris c and (ii) constrain its mass to 10.04(-3.10)(+4.53) M-Jup . If one adds the astrometry of beta Pictoris c, the mass is narrowed down to 9.15(-1.06)(+1.08) M-Jup. The inclusion of radial velocity measurements does not affect the orbital parameters significantly, but it does slightly decrease the mass estimate to 8.89(-0.75)(+0.75) M-Jup.With a semimajor axis of 2.68 +/- 0.02 au, a period of 1221 +/- 15 days, and an eccentricity of 0.32 +/- 0.02, the orbital parameters of beta Pictoris c are now constrained as precisely as those of beta Pictoris b. The orbital configuration is compatible with a high-order mean-motion resonance (7:1). The impact of the resonance on the planets' dynamics would then be negligible with respect to the secular perturbations, which might have played an important role in the eccentricity excitation of the outer planet.
Published: 2021

18. Constraining the Nature of the PDS 70 Protoplanets with VLTI/GRAVITY*

Author: Wang, J. J., Vigan, A., Lacour, S., Nowak, M., Stolker, T., De Rosa, R. J., Ginzburg, S., Gao, P., Abuter, R., Amorim, A., Asensio-Torres, R., Bauboeck, M., Benisty, M., Berger, J. P., Beust, H., Beuzit, J. -L., Blunt, S., Boccaletti, A., Bohn, A., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V., Clenet, Y., du Foresto, V. Coude, Cridland, A., Zeeuw, P. T. de, Dembet, R., Dexter, J., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Facchini, S., Gao, F., Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J., Haubois, X., Heissel, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houlle, M., Hubert, Z., Jimenez-Rosales, A., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Meyer, M., Kreidberg, L., Lagrange, A. -M., Lapeyrere, V., Bouquin, J. -B. Le, Lena, P., Lutz, D., Maire, A. -L., Menard, F., Merand, A., Molliere, P., Monnier, J. D., Mouillet, D., Mueller, A., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Pueyo, L., Rameau, J., Rodet, L., Rodriguez-Coira, G., Rousset, G., Scheithauer, S., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., Dishoeck, E. F. van, Vincent, F., Fellenberg, S. D. von, Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Wang, J. J., Vigan, A., Lacour, S., Nowak, M., Stolker, T., De Rosa, R. J., Ginzburg, S., Gao, P., Abuter, R., Amorim, A., Asensio-Torres, R., Bauboeck, M., Benisty, M., Berger, J. P., Beust, H., Beuzit, J. -L., Blunt, S., Boccaletti, A., Bohn, A., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V., Clenet, Y., du Foresto, V. Coude, Cridland, A., Zeeuw, P. T. de, Dembet, R., Dexter, J., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Facchini, S., Gao, F., Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J., Haubois, X., Heissel, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houlle, M., Hubert, Z., Jimenez-Rosales, A., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Meyer, M., Kreidberg, L., Lagrange, A. -M., Lapeyrere, V., Bouquin, J. -B. Le, Lena, P., Lutz, D., Maire, A. -L., Menard, F., Merand, A., Molliere, P., Monnier, J. D., Mouillet, D., Mueller, A., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Pueyo, L., Rameau, J., Rodet, L., Rodriguez-Coira, G., Rousset, G., Scheithauer, S., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., Dishoeck, E. F. van, Vincent, F., Fellenberg, S. D. von, Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., and Woillez, J.
Abstract: We present K-band interferometric observations of the PDS 70 protoplanets along with their host star using VLTI/GRAVITY. We obtained K-band spectra and 100 mu as precision astrometry of both PDS 70 b and c in two epochs, as well as spatially resolving the hot inner disk around the star. Rejecting unstable orbits, we found a nonzero eccentricity for PDS 70 b of 0.17 0.06, a near-circular orbit for PDS 70 c, and an orbital configuration that is consistent with the planets migrating into a 2:1 mean motion resonance. Enforcing dynamical stability, we obtained a 95% upper limit on the mass of PDS 70 b of 10 M-Jup, while the mass of PDS 70 c was unconstrained. The GRAVITY K-band spectra rules out pure blackbody models for the photospheres of both planets. Instead, the models with the most support from the data are planetary atmospheres that are dusty, but the nature of the dust is unclear. Any circumplanetary dust around these planets is not well constrained by the planets' 1-5 mu m spectral energy distributions (SEDs) and requires longer wavelength data to probe with SED analysis. However with VLTI/GRAVITY, we made the first observations of a circumplanetary environment with sub-astronomical-unit spatial resolution, placing an upper limit of 0.3 au on the size of a bright disk around PDS 70 b.
Published: 2021

19. Narrow belt of debris around the Sco-Cen star HD 141011

Author: Bonnefoy, M., Milli, J., Menard, F., Delorme, P., Chomez, A., Bonavita, M., Lagrange, A-M., Vigan, A., Augereau, J. C., Beuzit, J. L., Biller, B., Boccaletti, A., Chauvin, G., Desidera, S., Faramaz, V., Galicher, R., Gratton, R., Hinkley, S., Lazzoni, C., Matthews, E., Mesa, D., Mordasini, C., Mouillet, D., Olofsson, J., Pinte, C., Bonnefoy, M., Milli, J., Menard, F., Delorme, P., Chomez, A., Bonavita, M., Lagrange, A-M., Vigan, A., Augereau, J. C., Beuzit, J. L., Biller, B., Boccaletti, A., Chauvin, G., Desidera, S., Faramaz, V., Galicher, R., Gratton, R., Hinkley, S., Lazzoni, C., Matthews, E., Mesa, D., Mordasini, C., Mouillet, D., Olofsson, J., and Pinte, C.
Abstract: We initiated a deep-imaging survey of Scorpius-Centaurus A-F stars with predicted warm inner and cold outer belts of debris reminiscent of the architecture of emblematic systems such as HR 8799. We present resolved SPHERE images of a narrow ring of debris around the F5-type star HD 141011 that was observed as part of our survey in 2015, 2016, and 2019. The ring extends up to ~1.1" (~141 au) from the star in the IRDIS and IFS data obtained in 2016 and 2019. The disk is not detected in the 2015 data which are of poorer quality. The disks is best reproduced by models of a noneccentric ring centered on the star with an inclination of $69.1\pm0.9^{\circ}$, a position angle of $-24.6 \pm 1.7^{\circ}$, and a semimajor axis of $127.5\pm3.8$ au. The combination of radial velocity and imaging data excludes brown-dwarf (M>13.6 MJup) companions coplanar with the disk from 0.1 to 0.9 au and from 20 au up to 500 au (90% probability). HD 141011 adds to the growing list of debris disks that are resolved in Sco-Cen. It is one of the faintest disks that are resolved from the ground and has a radial extent and fractional width ($\sim$12.5%) reminiscent of Fomalhaut. Its moderate inclination and large semimajor axis make it a good target for the James Webb Space Telescope and should allow a deeper search for putative companions shaping the dust distribution., Comment: 13 pages, 10 figures. Paper II of our Sco-Cen imaging survey. Accepted in A&A
Published: 2021
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20. The mass of Beta Pictoris c from Beta Pictoris b orbital motion

Author: Lacour, S., Wang, J. J., Rodet, L., Nowak, M., Shangguan, J., Beust, H., Lagrange, A. -M., Abuter, R., Amorim, A., Asensio-Torres, R., Benisty, M., Berger, J. -P., Blunt, S., Boccaletti, A., Bohn, A., Bolzer, M. -L., Bonnefoy, M., Bonnet, H., Bourdarot, G., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., Dembet, R., Dexter, J., de Zeeuw, P. T., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Haubois, X., Heißel, G., Henning, Th., Hinkley, S., Hippler, S., Horrobin, M., Houllé, M., Hubert, Z., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Kreidberg, L., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Lutz, D., Maire, A. -L., Mérand, A., Mollière, P., Monnier, J. D., Mouillet, D., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Rickman, E., Pueyo, L., Rameau, J., Rousset, G., Rustamkulov, Z., Samland, M., Shimizu, T., Sing, D., Stadler, J., Stolker, T., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., Young, A., Collaboration, the GRAVITY, Lacour, S., Wang, J. J., Rodet, L., Nowak, M., Shangguan, J., Beust, H., Lagrange, A. -M., Abuter, R., Amorim, A., Asensio-Torres, R., Benisty, M., Berger, J. -P., Blunt, S., Boccaletti, A., Bohn, A., Bolzer, M. -L., Bonnefoy, M., Bonnet, H., Bourdarot, G., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., Dembet, R., Dexter, J., de Zeeuw, P. T., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Haubois, X., Heißel, G., Henning, Th., Hinkley, S., Hippler, S., Horrobin, M., Houllé, M., Hubert, Z., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Kreidberg, L., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Lutz, D., Maire, A. -L., Mérand, A., Mollière, P., Monnier, J. D., Mouillet, D., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Rickman, E., Pueyo, L., Rameau, J., Rousset, G., Rustamkulov, Z., Samland, M., Shimizu, T., Sing, D., Stadler, J., Stolker, T., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., Young, A., and Collaboration, the GRAVITY
Abstract: We aim to demonstrate that the presence and mass of an exoplanet can now be effectively derived from the astrometry of another exoplanet. We combined previous astrometry of $\beta$ Pictoris b with a new set of observations from the GRAVITY interferometer. The orbital motion of $\beta$ Pictoris b is fit using Markov chain Monte Carlo simulations in Jacobi coordinates. The inner planet, $\beta$ Pictoris c, was also reobserved at a separation of 96\,mas, confirming the previous orbital estimations. From the astrometry of planet b only, we can (i) detect the presence of $\beta$ Pictoris c and (ii) constrain its mass to $10.04^{+4.53}_{-3.10}\,M_{\rm Jup}$. If one adds the astrometry of $\beta$ Pictoris c, the mass is narrowed down to $9.15^{+1.08}_{-1.06}\,M_{\rm Jup}$. The inclusion of radial velocity measurements does not affect the orbital parameters significantly, but it does slightly decrease the mass estimate to $8.89^{+0.75}_{-0.75}\,M_{\rm Jup}$. With a semimajor axis of $2.68\pm0.02$\,au, a period of $1221\pm15$ days, and an eccentricity of $0.32\pm0.02$, the orbital parameters of $\beta$ Pictoris c are now constrained as precisely as those of $\beta$ Pictoris b. The orbital configuration is compatible with a high-order mean-motion resonance (7:1). The impact of the resonance on the planets' dynamics would then be negligible with respect to the secular perturbations, which might have played an important role in the eccentricity excitation of the outer planet., Comment: Accepted in A&A Letter
Published: 2021
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21. GRAVITY K-band spectroscopy of HD 206893 B: brown dwarf or exoplanet

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

Author: Lacour, S., Wang, J. J., Nowak, M., Pueyo, L., Eisenhauer, F., Lagrange, A. -M., Mollière, P., Abuter, R., Amorim, A., Asensio-Torres, R., Bauböck, M., Benisty, M., Berger, J. P., Beust, H., Blunt, S., Boccaletti, A., Bohn, A., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V., Clénet, Y., Cridland, A., de Zeeuw, P. T., Dembet, R., Dexter, J., Drescher, A., Duvert, G., Gao, F., Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Haubois, X., Heissel, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houllé, M., Hubert, Z., Jiménez-Rosales, A., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Kreidberg, L., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Lutz, D., Maire, A. -L., Mérand, A., Monnier, J. D., Mouillet, D., Muller, A., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Rameau, J., Rodet, L., Rodriguez-Coira, G., Rousset, G., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Stolker, T., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Lacour, S., Wang, J. J., Nowak, M., Pueyo, L., Eisenhauer, F., Lagrange, A. -M., Mollière, P., Abuter, R., Amorim, A., Asensio-Torres, R., Bauböck, M., Benisty, M., Berger, J. P., Beust, H., Blunt, S., Boccaletti, A., Bohn, A., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V., Clénet, Y., Cridland, A., de Zeeuw, P. T., Dembet, R., Dexter, J., Drescher, A., Duvert, G., Gao, F., Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J. H., Haubois, X., Heissel, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houllé, M., Hubert, Z., Jiménez-Rosales, A., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Kreidberg, L., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Lutz, D., Maire, A. -L., Mérand, A., Monnier, J. D., Mouillet, D., Muller, A., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Rameau, J., Rodet, L., Rodriguez-Coira, G., Rousset, G., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Stolker, T., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., and Woillez, J.
Abstract: Combining adaptive optics and interferometric observations results in a considerable contrast gain compared to single-telescope, extreme AO systems. Taking advantage of this, the ExoGRAVITY project is a survey of known young giant exoplanets located in the range of 0.1'' to 2'' from their stars. The observations provide astrometric data of unprecedented accuracy, being crucial for refining the orbital parameters of planets and illuminating their dynamical histories. Furthermore, GRAVITY will measure non-Keplerian perturbations due to planet-planet interactions in multi-planet systems and measure dynamical masses. Over time, repetitive observations of the exoplanets at medium resolution ($R=500$) will provide a catalogue of K-band spectra of unprecedented quality, for a number of exoplanets. The K-band has the unique properties that it contains many molecular signatures (CO, H$_2$O, CH$_4$, CO$_2$). This allows constraining precisely surface gravity, metallicity, and temperature, if used in conjunction with self-consistent models like Exo-REM. Further, we will use the parameter-retrieval algorithm petitRADTRANS to constrain the C/O ratio of the planets. Ultimately, we plan to produce the first C/O survey of exoplanets, kick-starting the difficult process of linking planetary formation with measured atomic abundances., Comment: SPIE 2020, invited talk
Published: 2021
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23. Constraining the Nature of the PDS 70 Protoplanets with VLTI/GRAVITY

Author: Wang, J. J., Vigan, A., Lacour, S., Nowak, M., Stolker, T., De Rosa, R. J., Ginzburg, S., Gao, P., Abuter, R., Amorim, A., Asensio-Torres, R., Baubck, M., Benisty, M., Berger, J. P., Beust, H., Beuzit, J. -L., Blunt, S., Boccaletti, A., Bohn, A., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., de Zeeuw, P. T., Dembet, R., Dexter, J., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Facchini, S., Gao, F., Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J., Haubois, X., Heißel, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houllé, M., Hubert, Z., Jiménez-Rosales, A., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Meyer, M., Kreidberg, L., Lagrange, A. -M., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Lutz, D., Maire, A. -L., Ménard, F., Mérand, A., Mollière, P., Monnier, J. D., Mouillet, D., Müller, A., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Pueyo, L., Rameau, J., Rodet, L., Rodríguez-Coira, G., Rousset, G., Scheithauer, S., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vincent, F., von Fellenberg, S. D., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Collaboration, The GRAVITY, Wang, J. J., Vigan, A., Lacour, S., Nowak, M., Stolker, T., De Rosa, R. J., Ginzburg, S., Gao, P., Abuter, R., Amorim, A., Asensio-Torres, R., Baubck, M., Benisty, M., Berger, J. P., Beust, H., Beuzit, J. -L., Blunt, S., Boccaletti, A., Bohn, A., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., de Zeeuw, P. T., Dembet, R., Dexter, J., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Facchini, S., Gao, F., Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J., Haubois, X., Heißel, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houllé, M., Hubert, Z., Jiménez-Rosales, A., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Meyer, M., Kreidberg, L., Lagrange, A. -M., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Lutz, D., Maire, A. -L., Ménard, F., Mérand, A., Mollière, P., Monnier, J. D., Mouillet, D., Müller, A., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Pueyo, L., Rameau, J., Rodet, L., Rodríguez-Coira, G., Rousset, G., Scheithauer, S., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vincent, F., von Fellenberg, S. D., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., and Collaboration, The GRAVITY
Abstract: We present K-band interferometric observations of the PDS 70 protoplanets along with their host star using VLTI/GRAVITY. We obtained K-band spectra and 100 $\mu$as precision astrometry of both PDS 70 b and c in two epochs, as well as spatially resolving the hot inner disk around the star. Rejecting unstable orbits, we found a nonzero eccentricity for PDS 70 b of $0.17 \pm 0.06$, a near-circular orbit for PDS 70 c, and an orbital configuration that is consistent with the planets migrating into a 2:1 mean motion resonance. Enforcing dynamical stability, we obtained a 95% upper limit on the mass of PDS 70 b of 10 $M_\textrm{Jup}$, while the mass of PDS 70 c was unconstrained. The GRAVITY K-band spectra rules out pure blackbody models for the photospheres of both planets. Instead, the models with the most support from the data are planetary atmospheres that are dusty, but the nature of the dust is unclear. Any circumplanetary dust around these planets is not well constrained by the planets' 1-5 $\mu$m spectral energy distributions (SEDs) and requires longer wavelength data to probe with SED analysis. However with VLTI/GRAVITY, we made the first observations of a circumplanetary environment with sub-au spatial resolution, placing an upper limit of 0.3~au on the size of a bright disk around PDS 70 b., Comment: 30 pages, 9 figures, Accepted for publication in AJ
Published: 2021
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24. A survey of the linear polarization of directly imaged exoplanets and brown dwarf companions with SPHERE-IRDIS. First polarimetric detections revealing disks around DH Tau B and GSC 6214-210 B

Author: van Holstein, R. G., Stolker, T., Jensen-Clem, R., Ginski, C., Milli, J., de Boer, J., Girard, J. H., Wahhaj, Z., Bohn, A. J., Millar-Blanchaer, M. A., Benisty, M., Bonnefoy, M., Chauvin, G., Dominik, C., Hinkley, S., Keller, C. U., Keppler, M., Langlois, M., Marino, S., Ménard, F., Perrot, C., Schmidt, T. O. B., Vigan, A., Zurlo, A., Snik, F., van Holstein, R. G., Stolker, T., Jensen-Clem, R., Ginski, C., Milli, J., de Boer, J., Girard, J. H., Wahhaj, Z., Bohn, A. J., Millar-Blanchaer, M. A., Benisty, M., Bonnefoy, M., Chauvin, G., Dominik, C., Hinkley, S., Keller, C. U., Keppler, M., Langlois, M., Marino, S., Ménard, F., Perrot, C., Schmidt, T. O. B., Vigan, A., Zurlo, A., and Snik, F.
Abstract: Young giant planets and brown dwarf companions emit near-infrared radiation that can be linearly polarized up to several percent. This polarization can reveal the presence of a circumsubstellar accretion disk, rotation-induced oblateness of the atmosphere, or an inhomogeneous distribution of atmospheric dust clouds. We measured the near-infrared linear polarization of 20 known directly imaged exoplanets and brown dwarf companions with the high-contrast imager SPHERE-IRDIS at the VLT. We reduced the data using the IRDAP pipeline to correct for the instrumental polarization and crosstalk with an absolute polarimetric accuracy <0.1% in the degree of polarization. We report the first detection of polarization originating from substellar companions, with a polarization of several tenths of a percent for DH Tau B and GSC 6214-210 B in H-band. By comparing the measured polarization with that of nearby stars, we find that the polarization is unlikely to be caused by interstellar dust. Because the companions have previously measured hydrogen emission lines and red colors, the polarization most likely originates from circumsubstellar disks. Through radiative transfer modeling, we constrain the position angles of the disks and find that the disks must have high inclinations. The presence of these disks as well as the misalignment of the disk of DH Tau B with the disk around its primary star suggest in situ formation of the companions. For the 18 other companions, we do not detect significant polarization and place subpercent upper limits on their degree of polarization. These non-detections may indicate the absence of circumsubstellar disks, a slow rotation rate of young companions, the upper atmospheres containing primarily submicron-sized dust grains, and/or limited cloud inhomogeneity. Finally, we present images of the circumstellar disks of DH Tau, GQ Lup, PDS 70, Beta Pic, and HD 106906., Comment: Accepted for publication in A&A. Shortened abstract. 29 pages, 22 figures
Published: 2021
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25. Retrieving scattering clouds and disequilibrium chemistry in the atmosphere of HR 8799e

Author: Mollière, P., Stolker, T., Lacour, S., Otten, G. P. P. L., Shangguan, J., Charnay, B., Molyarova, T., Nowak, M., Henning, Th., Marleau, G. -D., Semenov, D. A., van Dishoeck, E., Eisenhauer, F., Garcia, P., Lopez, R. Garcia, Girard, J. H., Greenbaum, A. Z., Hinkley, S., Kervella, P., Kreidberg, L., Maire, A. -L., Nasedkin, E., Pueyo, L., Snellen, I. A. G., Vigan, A., Wang, J., de Zeeuw, P. T., Zurlo, A., Mollière, P., Stolker, T., Lacour, S., Otten, G. P. P. L., Shangguan, J., Charnay, B., Molyarova, T., Nowak, M., Henning, Th., Marleau, G. -D., Semenov, D. A., van Dishoeck, E., Eisenhauer, F., Garcia, P., Lopez, R. Garcia, Girard, J. H., Greenbaum, A. Z., Hinkley, S., Kervella, P., Kreidberg, L., Maire, A. -L., Nasedkin, E., Pueyo, L., Snellen, I. A. G., Vigan, A., Wang, J., de Zeeuw, P. T., and Zurlo, A.
Abstract: Clouds are ubiquitous in exoplanet atmospheres and represent a challenge for the model interpretation of their spectra. Complex cloud models are too numerically costly for generating a large number of spectra, while more efficient models may be too strongly simplified. We aim to constrain the atmospheric properties of the directly imaged planet HR 8799e with a free retrieval approach. We use our radiative transfer code petitRADTRANS for generating spectra, which we couple to the PyMultiNest tool. We added the effect of multiple scattering which is important for treating clouds. Two cloud model parameterizations are tested: the first incorporates the mixing and settling of condensates, the second simply parameterizes the functional form of the opacity. In mock retrievals, using an inadequate cloud model may result in atmospheres that are more isothermal and less cloudy than the input. Applying our framework on observations of HR 8799e made with the GPI, SPHERE and GRAVITY, we find a cloudy atmosphere governed by disequilibrium chemistry, confirming previous analyses. We retrieve that ${\rm C/O}=0.60_{-0.08}^{+0.07}$. Other models have not yet produced a well constrained C/O value for this planet. The retrieved C/O values of both cloud models are consistent, while leading to different atmospheric structures: cloudy, or more isothermal and less cloudy. Fitting the observations with the self-consistent Exo-REM model leads to comparable results, while not constraining C/O. With data from the most sensitive instruments, retrieval analyses of directly imaged planets are possible. The inferred C/O ratio of HR 8799e is independent of the cloud model and thus appears to be a robust. This C/O is consistent with stellar, which could indicate that the HR 8799e formed outside the CO$_2$ or CO iceline. As it is the innermost planet of the system, this constraint could apply to all HR 8799 planets., Comment: Accepted for publication in A&A, 28 pages, 13 figures, updated author list
Published: 2020
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26. Direct confirmation of the radial-velocity planet beta Pictoris c

Author: Nowak, M., Lacour, S., Lagrange, A. -M., Rubini, P., Wang, J., Stolker, T., Abuter, R., Amorim, A., Asensio-Torres, R., Bauboeck, M., Benisty, M., Berger, J. P., Beust, H., Blunt, S., Boccaletti, A., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Charnay, B., Choquet, E., Christiaens, V., Clenet, Y., du Foresto, V. Coude, Cridland, A., de Zeeuw, P. T., Dembet, R., Dexter, J., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J., Grandjean, A., Haubois, X., Heissel, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houlle, M., Hubert, Z., Jimenez-Rosales, A., Jocou, L., Kammerer, J., Kervella, P., Keppler, M., Kreidberg, L., Kulikauskas, M., Lapeyrere, V., Le Bouquin, J. -B., Lena, P., Merand, A., Maire, A. -L., Molliere, P., Monnier, J. D., Mouillet, D., Mueller, A., Nasedkin, E., Ott, T., Otten, G., Paumard, T., Paladini, C., Perraut, K., Perrin, G., Pueyo, L., Pfuhl, O., Rameau, J., Rodet, L., Rodriguez-Coira, G., Rousset, G., Scheithauer, S., Shangguan, J., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Nowak, M., Lacour, S., Lagrange, A. -M., Rubini, P., Wang, J., Stolker, T., Abuter, R., Amorim, A., Asensio-Torres, R., Bauboeck, M., Benisty, M., Berger, J. P., Beust, H., Blunt, S., Boccaletti, A., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Charnay, B., Choquet, E., Christiaens, V., Clenet, Y., du Foresto, V. Coude, Cridland, A., de Zeeuw, P. T., Dembet, R., Dexter, J., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J., Grandjean, A., Haubois, X., Heissel, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houlle, M., Hubert, Z., Jimenez-Rosales, A., Jocou, L., Kammerer, J., Kervella, P., Keppler, M., Kreidberg, L., Kulikauskas, M., Lapeyrere, V., Le Bouquin, J. -B., Lena, P., Merand, A., Maire, A. -L., Molliere, P., Monnier, J. D., Mouillet, D., Mueller, A., Nasedkin, E., Ott, T., Otten, G., Paumard, T., Paladini, C., Perraut, K., Perrin, G., Pueyo, L., Pfuhl, O., Rameau, J., Rodet, L., Rodriguez-Coira, G., Rousset, G., Scheithauer, S., Shangguan, J., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., and Woillez, J.
Abstract: Context. Methods used to detect giant exoplanets can be broadly divided into two categories: indirect and direct. Indirect methods are more sensitive to planets with a small orbital period, whereas direct detection is more sensitive to planets orbiting at a large distance from their host star. This dichotomy makes it difficult to combine the two techniques on a single target at once.Aims. Simultaneous measurements made by direct and indirect techniques offer the possibility of determining the mass and luminosity of planets and a method of testing formation models. Here, we aim to show how long-baseline interferometric observations guided by radial-velocity can be used in such a way.Methods. We observed the recently-discovered giant planet beta Pictoris c with GRAVITY, mounted on the Very Large Telescope Interferometer.Results. This study constitutes the first direct confirmation of a planet discovered through radial velocity. We find that the planet has a temperature of T=125050 K and a dynamical mass of M=8.2 +/- 0.8 M-Jup. At 18.5 +/- 2.5 Myr, this puts beta Pic c close to a 'hot start' track, which is usually associated with formation via disk instability. Conversely, the planet orbits at a distance of 2.7 au, which is too close for disk instability to occur. The low apparent magnitude (M-K=14.3 +/- 0.1) favours a core accretion scenario.Conclusions. We suggest that this apparent contradiction is a sign of hot core accretion, for example, due to the mass of the planetary core or the existence of a high-temperature accretion shock during formation.
Published: 2020

27. Direct confirmation of the radial-velocity planet beta Pictoris c

Author: Nowak, M., Lacour, S., Lagrange, A. -M., Rubini, P., Wang, J., Stolker, T., Abuter, R., Amorim, A., Asensio-Torres, R., Bauboeck, M., Benisty, M., Berger, J. P., Beust, H., Blunt, S., Boccaletti, A., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Charnay, B., Choquet, E., Christiaens, V., Clenet, Y., du Foresto, V. Coude, Cridland, A., de Zeeuw, P. T., Dembet, R., Dexter, J., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J., Grandjean, A., Haubois, X., Heissel, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houlle, M., Hubert, Z., Jimenez-Rosales, A., Jocou, L., Kammerer, J., Kervella, P., Keppler, M., Kreidberg, L., Kulikauskas, M., Lapeyrere, V., Le Bouquin, J. -B., Lena, P., Merand, A., Maire, A. -L., Molliere, P., Monnier, J. D., Mouillet, D., Mueller, A., Nasedkin, E., Ott, T., Otten, G., Paumard, T., Paladini, C., Perraut, K., Perrin, G., Pueyo, L., Pfuhl, O., Rameau, J., Rodet, L., Rodriguez-Coira, G., Rousset, G., Scheithauer, S., Shangguan, J., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Nowak, M., Lacour, S., Lagrange, A. -M., Rubini, P., Wang, J., Stolker, T., Abuter, R., Amorim, A., Asensio-Torres, R., Bauboeck, M., Benisty, M., Berger, J. P., Beust, H., Blunt, S., Boccaletti, A., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Charnay, B., Choquet, E., Christiaens, V., Clenet, Y., du Foresto, V. Coude, Cridland, A., de Zeeuw, P. T., Dembet, R., Dexter, J., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J., Grandjean, A., Haubois, X., Heissel, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houlle, M., Hubert, Z., Jimenez-Rosales, A., Jocou, L., Kammerer, J., Kervella, P., Keppler, M., Kreidberg, L., Kulikauskas, M., Lapeyrere, V., Le Bouquin, J. -B., Lena, P., Merand, A., Maire, A. -L., Molliere, P., Monnier, J. D., Mouillet, D., Mueller, A., Nasedkin, E., Ott, T., Otten, G., Paumard, T., Paladini, C., Perraut, K., Perrin, G., Pueyo, L., Pfuhl, O., Rameau, J., Rodet, L., Rodriguez-Coira, G., Rousset, G., Scheithauer, S., Shangguan, J., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., and Woillez, J.
Abstract: Context. Methods used to detect giant exoplanets can be broadly divided into two categories: indirect and direct. Indirect methods are more sensitive to planets with a small orbital period, whereas direct detection is more sensitive to planets orbiting at a large distance from their host star. This dichotomy makes it difficult to combine the two techniques on a single target at once.Aims. Simultaneous measurements made by direct and indirect techniques offer the possibility of determining the mass and luminosity of planets and a method of testing formation models. Here, we aim to show how long-baseline interferometric observations guided by radial-velocity can be used in such a way.Methods. We observed the recently-discovered giant planet beta Pictoris c with GRAVITY, mounted on the Very Large Telescope Interferometer.Results. This study constitutes the first direct confirmation of a planet discovered through radial velocity. We find that the planet has a temperature of T=125050 K and a dynamical mass of M=8.2 +/- 0.8 M-Jup. At 18.5 +/- 2.5 Myr, this puts beta Pic c close to a 'hot start' track, which is usually associated with formation via disk instability. Conversely, the planet orbits at a distance of 2.7 au, which is too close for disk instability to occur. The low apparent magnitude (M-K=14.3 +/- 0.1) favours a core accretion scenario.Conclusions. We suggest that this apparent contradiction is a sign of hot core accretion, for example, due to the mass of the planetary core or the existence of a high-temperature accretion shock during formation.
Published: 2020

28. Direct confirmation of the radial-velocity planet $\beta$ Pic c

Author: Nowak, M., Lacour, S., Lagrange, A. -M., Rubini, P., Wang, J., Stolker, T., Amorim, A., Asensio-Torres, R., Bauböck, M., Benisty, M., Berger, J. P., Beust, H., Blunt, S., Boccaletti, A., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Charnay, B., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., de Zeeuw, P. T., Dembet, R., Dexter, J., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J., Haubois, X., Heißel, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houllé, M., Hubert, Z., Jiménez-Rosales, A., Jocou, L., Kammerer, J., Kervella, P., Keppler, M., Kreidberg, L., Kulikauskas, M., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Mérand, A., Maire, A. -L., Mollière, P., Monnier, J. D., Mouillet, D., Müller, A., Nasedkin, E., Ott, T., Otten, G., Paumard, T., Paladini, C., Perraut, K., Perrin, G., Pueyo, L., Pfuhl, O., Rameau, J., Rodet, L., Rodríguez-Coira, G., Rousset, G., Scheithauer, S., Shangguan, J., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Collaboration, the GRAVITY, Nowak, M., Lacour, S., Lagrange, A. -M., Rubini, P., Wang, J., Stolker, T., Amorim, A., Asensio-Torres, R., Bauböck, M., Benisty, M., Berger, J. P., Beust, H., Blunt, S., Boccaletti, A., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Charnay, B., Choquet, E., Christiaens, V., Clénet, Y., Foresto, V. Coudé du, Cridland, A., de Zeeuw, P. T., Dembet, R., Dexter, J., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J., Haubois, X., Heißel, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houllé, M., Hubert, Z., Jiménez-Rosales, A., Jocou, L., Kammerer, J., Kervella, P., Keppler, M., Kreidberg, L., Kulikauskas, M., Lapeyrère, V., Bouquin, J. -B. Le, Léna, P., Mérand, A., Maire, A. -L., Mollière, P., Monnier, J. D., Mouillet, D., Müller, A., Nasedkin, E., Ott, T., Otten, G., Paumard, T., Paladini, C., Perraut, K., Perrin, G., Pueyo, L., Pfuhl, O., Rameau, J., Rodet, L., Rodríguez-Coira, G., Rousset, G., Scheithauer, S., Shangguan, J., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., and Collaboration, the GRAVITY
Abstract: Methods used to detect giant exoplanets can be broadly divided into two categories: indirect and direct. Indirect methods are more sensitive to planets with a small orbital period, whereas direct detection is more sensitive to planets orbiting at a large distance from their host star. %, and thus on long orbital period. This dichotomy makes it difficult to combine the two techniques on a single target at once. Simultaneous measurements made by direct and indirect techniques offer the possibility of determining the mass and luminosity of planets and a method of testing formation models. Here, we aim to show how long-baseline interferometric observations guided by radial-velocity can be used in such a way. We observed the recently-discovered giant planet $\beta$ Pictoris c with GRAVITY, mounted on the Very Large Telescope Interferometer (VLTI). This study constitutes the first direct confirmation of a planet discovered through radial velocity. We find that the planet has a temperature of $T = 1250\pm50$\,K and a dynamical mass of $M = 8.2\pm0.8\,M_{\rm Jup}$. At $18.5\pm2.5$\,Myr, this puts $\beta$ Pic c close to a 'hot start' track, which is usually associated with formation via disk instability. Conversely, the planet orbits at a distance of 2.7\,au, which is too close for disk instability to occur. The low apparent magnitude ($M_{\rm K} = 14.3 \pm 0.1$) favours a core accretion scenario. We suggest that this apparent contradiction is a sign of hot core accretion, for example, due to the mass of the planetary core or the existence of a high-temperature accretion shock during formation., Comment: 10 pages
Published: 2020
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29. Retrieving scattering clouds and disequilibrium chemistry in the atmosphere of HR 8799e

Author: Mollière, P., Stolker, T., Lacour, S., Otten, G. P. P. L., Shangguan, J., Charnay, B., Molyarova, T., Nowak, M., Henning, Th., Marleau, G. -D., Semenov, D. A., van Dishoeck, E., Eisenhauer, F., Garcia, P., Lopez, R. Garcia, Girard, J. H., Greenbaum, A. Z., Hinkley, S., Kervella, P., Kreidberg, L., Maire, A. -L., Nasedkin, E., Pueyo, L., Snellen, I. A. G., Vigan, A., Wang, J., de Zeeuw, P. T., Zurlo, A., Mollière, P., Stolker, T., Lacour, S., Otten, G. P. P. L., Shangguan, J., Charnay, B., Molyarova, T., Nowak, M., Henning, Th., Marleau, G. -D., Semenov, D. A., van Dishoeck, E., Eisenhauer, F., Garcia, P., Lopez, R. Garcia, Girard, J. H., Greenbaum, A. Z., Hinkley, S., Kervella, P., Kreidberg, L., Maire, A. -L., Nasedkin, E., Pueyo, L., Snellen, I. A. G., Vigan, A., Wang, J., de Zeeuw, P. T., and Zurlo, A.
Abstract: Clouds are ubiquitous in exoplanet atmospheres and represent a challenge for the model interpretation of their spectra. Complex cloud models are too numerically costly for generating a large number of spectra, while more efficient models may be too strongly simplified. We aim to constrain the atmospheric properties of the directly imaged planet HR 8799e with a free retrieval approach. We use our radiative transfer code petitRADTRANS for generating spectra, which we couple to the PyMultiNest tool. We added the effect of multiple scattering which is important for treating clouds. Two cloud model parameterizations are tested: the first incorporates the mixing and settling of condensates, the second simply parameterizes the functional form of the opacity. In mock retrievals, using an inadequate cloud model may result in atmospheres that are more isothermal and less cloudy than the input. Applying our framework on observations of HR 8799e made with the GPI, SPHERE and GRAVITY, we find a cloudy atmosphere governed by disequilibrium chemistry, confirming previous analyses. We retrieve that ${\rm C/O}=0.60_{-0.08}^{+0.07}$. Other models have not yet produced a well constrained C/O value for this planet. The retrieved C/O values of both cloud models are consistent, while leading to different atmospheric structures: cloudy, or more isothermal and less cloudy. Fitting the observations with the self-consistent Exo-REM model leads to comparable results, while not constraining C/O. With data from the most sensitive instruments, retrieval analyses of directly imaged planets are possible. The inferred C/O ratio of HR 8799e is independent of the cloud model and thus appears to be a robust. This C/O is consistent with stellar, which could indicate that the HR 8799e formed outside the CO$_2$ or CO iceline. As it is the innermost planet of the system, this constraint could apply to all HR 8799 planets., Comment: Accepted for publication in A&A, 28 pages, 13 figures, updated author list
Published: 2020
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30. A Warm Jupiter-sized Planet Transiting the Pre-main-sequence Star V1298 Tau

Author: David, TJ, David, TJ, Cody, AM, Hedges, CL, Mamajek, EE, Hillenbrand, LA, Ciardi, DR, Beichman, CA, Petigura, EA, Fulton, BJ, Isaacson, HT, Howard, AW, Gagné, J, Saunders, NK, Rebull, LM, Stauffer, JR, Vasisht, G, Hinkley, S, David, TJ, David, TJ, Cody, AM, Hedges, CL, Mamajek, EE, Hillenbrand, LA, Ciardi, DR, Beichman, CA, Petigura, EA, Fulton, BJ, Isaacson, HT, Howard, AW, Gagné, J, Saunders, NK, Rebull, LM, Stauffer, JR, Vasisht, G, and Hinkley, S
Abstract: We report the detection of V1298 Tau b, a warm Jupiter-sized planet (R P = 0.91 ± 0.05 R Jup, P = 24.1 days) transiting a young solar analog with an estimated age of 23 Myr. The star and its planet belong to Group 29, a young association in the foreground of the Taurus-Auriga star-forming region. While hot Jupiters have been previously reported around young stars, those planets are non-transiting and near-term atmospheric characterization is not feasible. The V1298 Tau system is a compelling target for follow-up study through transmission spectroscopy and Doppler tomography owing to the transit depth (0.5%), host star brightness (K s = 8.1 mag), and rapid stellar rotation (= 23 km s-1). Although the planet is Jupiter-sized, its mass is currently unknown due to high-amplitude radial velocity jitter. Nevertheless, V1298 Tau b may help constrain formation scenarios for at least one class of close-in exoplanets, providing a window into the nascent evolution of planetary interiors and atmospheres.
Published: 2019

31. Investigating the presence of two belts in the HD 15115 system

Author: Engler, N., Boccaletti, A., Schmid, H. M., Milli, J., Augereau, J. -C., Mazoyer, J., Maire, A. -L., Henning, T., Avenhaus, H., Baudoz, P., Feldt, M., Galicher, R., Hinkley, S., Lagrange, A. -M., Mawet, D., Olofsson, J., Pantin, E., Perrot, C., Stapelfeldt, K., Engler, N., Boccaletti, A., Schmid, H. M., Milli, J., Augereau, J. -C., Mazoyer, J., Maire, A. -L., Henning, T., Avenhaus, H., Baudoz, P., Feldt, M., Galicher, R., Hinkley, S., Lagrange, A. -M., Mawet, D., Olofsson, J., Pantin, E., Perrot, C., and Stapelfeldt, K.
Abstract: We present new observations of the edge-on debris disk around HD 15115 (F star at 48.2 pc) obtained in the near-IR. We search for observational evidence for a second inner planetesimal ring in the system. We obtained total intensity and polarimetric data in the broad bands J and H and processed the data with differential imaging techniques achieving an angular resolution of about 40 mas. We observe an axisymmetric planetesimal belt with a radius of $\sim$2$''$, an inclination of $85.8^{\circ} \pm 0.7^{\circ}$ and position angle of 278.9$^{\circ} \pm 0.1^{\circ}$. A grid of models describing the spatial distribution of the grains in the disk is generated to constrain the geometric parameters of the disk and to explore the presence of a second belt. We perform a photometric analysis of the data and compare disk brightness in two bands in scattered and in polarized light. The analysis shows that the west side is $\sim$2.5 times brighter in total intensity than the east side in both bands, while for polarized light in the J band this ratio is only 1.25. The maximum polarization fraction is 15--20% at $r\sim$2.5$''$. We also find that the J - H color of the disk appears to be red for the radial separations $r\lesssim2''$ and is getting bluer for the larger separations. This apparent change of disk color from red to blue with an increasing radial separation could be explained by the decreasing average grain size with distance. The presence of an additional inner belt slightly inclined with respect to the main planetesimal belt is suspected from the polarized intensity image but the analysis and modeling presented here cannot establish a firm conclusion due to the faintness of the disk and its high inclination., Comment: 23 pages, 21 figures typos corrected
Published: 2018
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32. Investigating the presence of two belts in the HD 15115 system

Author: Engler, N., Boccaletti, A., Schmid, H. M., Milli, J., Augereau, J. -C., Mazoyer, J., Maire, A. -L., Henning, T., Avenhaus, H., Baudoz, P., Feldt, M., Galicher, R., Hinkley, S., Lagrange, A. -M., Mawet, D., Olofsson, J., Pantin, E., Perrot, C., Stapelfeldt, K., Engler, N., Boccaletti, A., Schmid, H. M., Milli, J., Augereau, J. -C., Mazoyer, J., Maire, A. -L., Henning, T., Avenhaus, H., Baudoz, P., Feldt, M., Galicher, R., Hinkley, S., Lagrange, A. -M., Mawet, D., Olofsson, J., Pantin, E., Perrot, C., and Stapelfeldt, K.
Abstract: We present new observations of the edge-on debris disk around HD 15115 (F star at 48.2 pc) obtained in the near-IR. We search for observational evidence for a second inner planetesimal ring in the system. We obtained total intensity and polarimetric data in the broad bands J and H and processed the data with differential imaging techniques achieving an angular resolution of about 40 mas. We observe an axisymmetric planetesimal belt with a radius of $\sim$2$''$, an inclination of $85.8^{\circ} \pm 0.7^{\circ}$ and position angle of 278.9$^{\circ} \pm 0.1^{\circ}$. A grid of models describing the spatial distribution of the grains in the disk is generated to constrain the geometric parameters of the disk and to explore the presence of a second belt. We perform a photometric analysis of the data and compare disk brightness in two bands in scattered and in polarized light. The analysis shows that the west side is $\sim$2.5 times brighter in total intensity than the east side in both bands, while for polarized light in the J band this ratio is only 1.25. The maximum polarization fraction is 15--20% at $r\sim$2.5$''$. We also find that the J - H color of the disk appears to be red for the radial separations $r\lesssim2''$ and is getting bluer for the larger separations. This apparent change of disk color from red to blue with an increasing radial separation could be explained by the decreasing average grain size with distance. The presence of an additional inner belt slightly inclined with respect to the main planetesimal belt is suspected from the polarized intensity image but the analysis and modeling presented here cannot establish a firm conclusion due to the faintness of the disk and its high inclination., Comment: 23 pages, 21 figures typos corrected
Published: 2018
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33. Evidence that the directly imaged planet HD 131399 Ab Is a Background Star

Author: Nielsen, EL, Nielsen, EL, Rosa, RJD, Rameau, J, Wang, JJ, Esposito, TM, Millar-Blanchaer, MA, Marois, C, Vigan, A, Ammons, SM, Artigau, E, Bailey, VP, Blunt, S, Bulger, J, Chilcote, J, Cotten, T, Doyon, R, Duchêne, G, Fabrycky, D, Fitzgerald, MP, Follette, KB, Gerard, BL, Goodsell, SJ, Graham, JR, Greenbaum, AZ, Hibon, P, Hinkley, S, Hung, LW, Ingraham, P, Jensen-Clem, R, Kalas, P, Konopacky, Q, Larkin, JE, MacIntosh, B, Maire, J, Marchis, F, Metchev, S, Morzinski, KM, Murray-Clay, RA, Oppenheimer, R, Palmer, D, Patience, J, Perrin, M, Poyneer, L, Pueyo, L, Rafikov, RR, Rajan, A, Rantakyrö, FT, Ruffio, JB, Savransky, D, Schneider, AC, Sivaramakrishnan, A, Song, I, Soummer, R, Thomas, S, Wallace, JK, Ward-Duong, K, Wiktorowicz, S, Wolff, S, Nielsen, EL, Nielsen, EL, Rosa, RJD, Rameau, J, Wang, JJ, Esposito, TM, Millar-Blanchaer, MA, Marois, C, Vigan, A, Ammons, SM, Artigau, E, Bailey, VP, Blunt, S, Bulger, J, Chilcote, J, Cotten, T, Doyon, R, Duchêne, G, Fabrycky, D, Fitzgerald, MP, Follette, KB, Gerard, BL, Goodsell, SJ, Graham, JR, Greenbaum, AZ, Hibon, P, Hinkley, S, Hung, LW, Ingraham, P, Jensen-Clem, R, Kalas, P, Konopacky, Q, Larkin, JE, MacIntosh, B, Maire, J, Marchis, F, Metchev, S, Morzinski, KM, Murray-Clay, RA, Oppenheimer, R, Palmer, D, Patience, J, Perrin, M, Poyneer, L, Pueyo, L, Rafikov, RR, Rajan, A, Rantakyrö, FT, Ruffio, JB, Savransky, D, Schneider, AC, Sivaramakrishnan, A, Song, I, Soummer, R, Thomas, S, Wallace, JK, Ward-Duong, K, Wiktorowicz, S, and Wolff, S
Abstract: We present evidence that the recently discovered, directly imaged planet HD 131399 Ab is a background star with nonzero proper motion. From new JHK1L′ photometry and spectroscopy obtained with the Gemini Planet Imager, VLT/SPHERE, and Keck/NIRC2, and a reanalysis of the discovery data obtained with VLT/SPHERE, we derive colors, spectra, and astrometry for HD 131399 Ab. The broader wavelength coverage and higher data quality allow us to reinvestigate its status. Its near-infrared spectral energy distribution excludes spectral types later than L0 and is consistent with a K or M dwarf, which are the most likely candidates for a background object in this direction at the apparent magnitude observed. If it were a physically associated object, the projected velocity of HD 131399 Ab would exceed escape velocity given the mass and distance to HD 131399 A. We show that HD 131399 Ab is also not following the expected track for a stationary background star at infinite distance. Solving for the proper motion and parallax required to explain the relative motion of HD 131399 Ab, we find a proper motion of 12.3 mas yr-1. When compared to predicted background objects drawn from a galactic model, we find this proper motion to be high but consistent with the top 4% fastest-moving background stars. From our analysis, we conclude that HD 131399 Ab is a background K or M dwarf.
Published: 2017

34. Project 1640 Observations of Brown Dwarf GJ 758 B : Near-infrared Spectrum and Atmospheric Modeling

Author: Nilsson, Ricky, Veicht, A., Godfrey, P. A. Giorla, Rice, E. L., Aguilar, J., Pueyo, L., Roberts, L. C., Oppenheimer, R., Brenner, D., Luszcz-Cook, S. H., Bacchus, E., Beichman, C., Burruss, R., Cady, E., Dekany, R., Fergus, R., Hillenbrand, L., Hinkley, S., King, D., Lockhart, T., Parry, I. R., Sivaramakrishnan, A., Soummer, R., Vasisht, G., Zhai, C., Zimmerman, N. T., Nilsson, Ricky, Veicht, A., Godfrey, P. A. Giorla, Rice, E. L., Aguilar, J., Pueyo, L., Roberts, L. C., Oppenheimer, R., Brenner, D., Luszcz-Cook, S. H., Bacchus, E., Beichman, C., Burruss, R., Cady, E., Dekany, R., Fergus, R., Hillenbrand, L., Hinkley, S., King, D., Lockhart, T., Parry, I. R., Sivaramakrishnan, A., Soummer, R., Vasisht, G., Zhai, C., and Zimmerman, N. T.
Abstract: The nearby Sun-like star GJ 758 hosts a cold substellar companion, GJ 758 B, at a projected separation of l less than or similar to 30 au, previously detected in high-contrast multi-band photometric observations. In order to better constrain the companion's physical characteristics, we acquired the first low-resolution (R similar to 50) near-infrared spectrum of it using the high-contrast hyperspectral imaging instrument Project 1640 on Palomar Observatory's 5 m Hale telescope. We obtained simultaneous images in 32 wavelength channels covering the Y, J, and H bands (similar to 9521770 nm), and used data processing techniques based on principal component analysis to efficiently subtract chromatic background speckle-noise. GJ 758 B was detected in four epochs during 2013 and 2014. Basic astrometric measurements confirm its apparent northwest trajectory relative to the primary star, with no clear signs of orbital curvature. Spectra of SpeX/IRTF observed T dwarfs were compared to the combined spectrum of GJ 758 B, with chi(2) minimization suggesting a best fit for spectral type T7.0 +/- 1.0, but with a shallow minimum over T5T8. Fitting of synthetic spectra from the BT-Settl13 model atmospheres gives an effective temperature T-eff = 741 +/- 25 K and surface gravity log g=4.3 +/- 0.5 dex (cgs). Our derived best-fit spectral type and effective temperature from modeling of the low-resolution spectrum suggest a slightly earlier and hotter companion than previous findings from photometric data, but do not rule out current results, and confirm GJ 758 B as one of the coolest sub-stellar companions to a Sun-like star to date.
Published: 2017
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35. Project 1640 Observations of Brown Dwarf GJ 758 B: Near-Infrared Spectrum and Atmospheric Modeling

Author: Nilsson, R., Veicht, A., Godfrey, P. A. Giorla, Rice, E. L., Aguilar, J., Pueyo, L., Roberts Jr., L. C., Oppenheimer, R., Brenner, D., Luszcz-Cook, S. H., Bacchus, E., Beichman, C., Burruss, R., Cady, E., Dekany, R., Fergus, R., Hillenbrand, L., Hinkley, S., King, D., Lockhart, T., Parry, I. R., Sivaramakrishnan, A., Soummer, R., Vasisht, G., Zhai, C., Zimmerman, N. T., Nilsson, R., Veicht, A., Godfrey, P. A. Giorla, Rice, E. L., Aguilar, J., Pueyo, L., Roberts Jr., L. C., Oppenheimer, R., Brenner, D., Luszcz-Cook, S. H., Bacchus, E., Beichman, C., Burruss, R., Cady, E., Dekany, R., Fergus, R., Hillenbrand, L., Hinkley, S., King, D., Lockhart, T., Parry, I. R., Sivaramakrishnan, A., Soummer, R., Vasisht, G., Zhai, C., and Zimmerman, N. T.
Abstract: The nearby Sun-like star GJ 758 hosts a cold substellar companion, GJ 758 B, at a projected separation of $\lesssim$30 AU, previously detected in high-contrast multi-band photometric observations. In order to better constrain the companion's physical characteristics, we acquired the first low-resolution ($R \sim 50$) near-infrared spectrum of it using the high-contrast hyperspectral imaging instrument Project 1640 on Palomar Observatory's 5-m Hale telescope. We obtained simultaneous images in 32 wavelength channels covering the $Y$, $J$, and $H$ bands ($\sim$952-1770 nm), and used data processing techniques based on principal component analysis to efficiently subtract chromatic background speckle-noise. GJ 758 B was detected in four epochs during 2013 and 2014. Basic astrometric measurements confirm its apparent northwest trajectory relative to the primary star, with no clear signs of orbital curvature. Spectra of SpeX/IRTF observed T dwarfs were compared to the combined spectrum of GJ 758 B, with ${\chi}^2$ minimization suggesting a best fit for spectral type T7.0$\pm$1.0, but with a shallow minimum over T5-T8. Fitting of synthetic spectra from the BT-Settl13 model atmospheres gives an effective temperature $T_{\text{eff}}=741 \pm 25$ K and surface gravity $\log g = 4.3 \pm 0.5$ dex (cgs). Our derived best-fit spectral type and effective temperature from modeling of the low-resolution spectrum suggest a slightly earlier and hotter companion than previous findings from photometric data, but do not rule out current results, and confirm GJ 758 B as one of the coolest sub-stellar companions to a Sun-like star to date., Comment: Accepted for publication in ApJ, 13 pages, 11 figures v2 updated with minor edits from corrected proofs
Published: 2017
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36. Polarized disk emission from Herbig Ae/Be stars observed using Gemini Planet Imager: HD 144432, HD 150193, HD 163296, and HD 169142

Author: Monnier, John D., Harries, T. J., Aarnio, A., Adams, F., Andrews, S., Calvet, N., Espaillat, C., Hartmann, L., Hinkley, S., Kraus, S., McClure, M., Oppenheimer, R., Perrin, M., Wilner, D., Monnier, John D., Harries, T. J., Aarnio, A., Adams, F., Andrews, S., Calvet, N., Espaillat, C., Hartmann, L., Hinkley, S., Kraus, S., McClure, M., Oppenheimer, R., Perrin, M., and Wilner, D.
Abstract: In order to look for signs of on-going planet formation in young disks, we carried out the first J-band polarized emission imaging of the Herbig Ae/Be stars HD 150193, HD 163296, and HD 169142 using the Gemini Planet Imager (GPI), along with new H band observations of HD 144432. We confirm the complex "double ring" structure for the nearly face-on system HD 169142 first seen in H-band, finding the outer ring to be substantially redder than the inner one in polarized intensity. Using radiative transfer modeling, we developed a physical model that explains the full spectral energy distribution (SED) and J- and H-band surface brightness profiles, suggesting that the differential color of the two rings could come from reddened starlight traversing the inner wall and may not require differences in grain properties. In addition, we clearly detect an elongated, off-center ring in HD 163296 (MWC 275), locating the scattering surface to be 18 AU above the midplane at a radial distance of 77 AU, co-spatial with a ring seen at 1.3mm by ALMA linked to the CO snow line. Lastly, we report a weak tentative detection of scattered light for HD 150193 (MWC 863) and a non-detection for HD 144432; the stellar companion known for each of these targets has likely disrupted the material in the outer disk of the primary star. For HD 163296 and HD 169142, the prominent outer rings we detect could be evidence for giant planet formation in the outer disk or a manifestation of large-scale dust growth processes possibly related to snow-line chemistry., Comment: Accepted Astrophysical Journal
Published: 2017
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37. Evidence that the directly imaged planet HD 131399 Ab Is a Background Star

Author: Nielsen, EL, Nielsen, EL, Rosa, RJD, Rameau, J, Wang, JJ, Esposito, TM, Millar-Blanchaer, MA, Marois, C, Vigan, A, Ammons, SM, Artigau, E, Bailey, VP, Blunt, S, Bulger, J, Chilcote, J, Cotten, T, Doyon, R, Duchêne, G, Fabrycky, D, Fitzgerald, MP, Follette, KB, Gerard, BL, Goodsell, SJ, Graham, JR, Greenbaum, AZ, Hibon, P, Hinkley, S, Hung, LW, Ingraham, P, Jensen-Clem, R, Kalas, P, Konopacky, Q, Larkin, JE, MacIntosh, B, Maire, J, Marchis, F, Metchev, S, Morzinski, KM, Murray-Clay, RA, Oppenheimer, R, Palmer, D, Patience, J, Perrin, M, Poyneer, L, Pueyo, L, Rafikov, RR, Rajan, A, Rantakyrö, FT, Ruffio, JB, Savransky, D, Schneider, AC, Sivaramakrishnan, A, Song, I, Soummer, R, Thomas, S, Wallace, JK, Ward-Duong, K, Wiktorowicz, S, Wolff, S, Nielsen, EL, Nielsen, EL, Rosa, RJD, Rameau, J, Wang, JJ, Esposito, TM, Millar-Blanchaer, MA, Marois, C, Vigan, A, Ammons, SM, Artigau, E, Bailey, VP, Blunt, S, Bulger, J, Chilcote, J, Cotten, T, Doyon, R, Duchêne, G, Fabrycky, D, Fitzgerald, MP, Follette, KB, Gerard, BL, Goodsell, SJ, Graham, JR, Greenbaum, AZ, Hibon, P, Hinkley, S, Hung, LW, Ingraham, P, Jensen-Clem, R, Kalas, P, Konopacky, Q, Larkin, JE, MacIntosh, B, Maire, J, Marchis, F, Metchev, S, Morzinski, KM, Murray-Clay, RA, Oppenheimer, R, Palmer, D, Patience, J, Perrin, M, Poyneer, L, Pueyo, L, Rafikov, RR, Rajan, A, Rantakyrö, FT, Ruffio, JB, Savransky, D, Schneider, AC, Sivaramakrishnan, A, Song, I, Soummer, R, Thomas, S, Wallace, JK, Ward-Duong, K, Wiktorowicz, S, and Wolff, S
Abstract: We present evidence that the recently discovered, directly imaged planet HD 131399 Ab is a background star with nonzero proper motion. From new JHK1L′ photometry and spectroscopy obtained with the Gemini Planet Imager, VLT/SPHERE, and Keck/NIRC2, and a reanalysis of the discovery data obtained with VLT/SPHERE, we derive colors, spectra, and astrometry for HD 131399 Ab. The broader wavelength coverage and higher data quality allow us to reinvestigate its status. Its near-infrared spectral energy distribution excludes spectral types later than L0 and is consistent with a K or M dwarf, which are the most likely candidates for a background object in this direction at the apparent magnitude observed. If it were a physically associated object, the projected velocity of HD 131399 Ab would exceed escape velocity given the mass and distance to HD 131399 A. We show that HD 131399 Ab is also not following the expected track for a stationary background star at infinite distance. Solving for the proper motion and parallax required to explain the relative motion of HD 131399 Ab, we find a proper motion of 12.3 mas yr-1. When compared to predicted background objects drawn from a galactic model, we find this proper motion to be high but consistent with the top 4% fastest-moving background stars. From our analysis, we conclude that HD 131399 Ab is a background K or M dwarf.
Published: 2017

38. Project 1640 Observations of Brown Dwarf GJ 758 B: Near-Infrared Spectrum and Atmospheric Modeling

Author: Nilsson, R., Veicht, A., Godfrey, P. A. Giorla, Rice, E. L., Aguilar, J., Pueyo, L., Roberts Jr., L. C., Oppenheimer, R., Brenner, D., Luszcz-Cook, S. H., Bacchus, E., Beichman, C., Burruss, R., Cady, E., Dekany, R., Fergus, R., Hillenbrand, L., Hinkley, S., King, D., Lockhart, T., Parry, I. R., Sivaramakrishnan, A., Soummer, R., Vasisht, G., Zhai, C., Zimmerman, N. T., Nilsson, R., Veicht, A., Godfrey, P. A. Giorla, Rice, E. L., Aguilar, J., Pueyo, L., Roberts Jr., L. C., Oppenheimer, R., Brenner, D., Luszcz-Cook, S. H., Bacchus, E., Beichman, C., Burruss, R., Cady, E., Dekany, R., Fergus, R., Hillenbrand, L., Hinkley, S., King, D., Lockhart, T., Parry, I. R., Sivaramakrishnan, A., Soummer, R., Vasisht, G., Zhai, C., and Zimmerman, N. T.
Abstract: The nearby Sun-like star GJ 758 hosts a cold substellar companion, GJ 758 B, at a projected separation of $\lesssim$30 AU, previously detected in high-contrast multi-band photometric observations. In order to better constrain the companion's physical characteristics, we acquired the first low-resolution ($R \sim 50$) near-infrared spectrum of it using the high-contrast hyperspectral imaging instrument Project 1640 on Palomar Observatory's 5-m Hale telescope. We obtained simultaneous images in 32 wavelength channels covering the $Y$, $J$, and $H$ bands ($\sim$952-1770 nm), and used data processing techniques based on principal component analysis to efficiently subtract chromatic background speckle-noise. GJ 758 B was detected in four epochs during 2013 and 2014. Basic astrometric measurements confirm its apparent northwest trajectory relative to the primary star, with no clear signs of orbital curvature. Spectra of SpeX/IRTF observed T dwarfs were compared to the combined spectrum of GJ 758 B, with ${\chi}^2$ minimization suggesting a best fit for spectral type T7.0$\pm$1.0, but with a shallow minimum over T5-T8. Fitting of synthetic spectra from the BT-Settl13 model atmospheres gives an effective temperature $T_{\text{eff}}=741 \pm 25$ K and surface gravity $\log g = 4.3 \pm 0.5$ dex (cgs). Our derived best-fit spectral type and effective temperature from modeling of the low-resolution spectrum suggest a slightly earlier and hotter companion than previous findings from photometric data, but do not rule out current results, and confirm GJ 758 B as one of the coolest sub-stellar companions to a Sun-like star to date., Comment: Accepted for publication in ApJ, 13 pages, 11 figures v2 updated with minor edits from corrected proofs
Published: 2017
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39. Polarized disk emission from Herbig Ae/Be stars observed using Gemini Planet Imager: HD 144432, HD 150193, HD 163296, and HD 169142

Author: Monnier, John D., Harries, T. J., Aarnio, A., Adams, F., Andrews, S., Calvet, N., Espaillat, C., Hartmann, L., Hinkley, S., Kraus, S., McClure, M., Oppenheimer, R., Perrin, M., Wilner, D., Monnier, John D., Harries, T. J., Aarnio, A., Adams, F., Andrews, S., Calvet, N., Espaillat, C., Hartmann, L., Hinkley, S., Kraus, S., McClure, M., Oppenheimer, R., Perrin, M., and Wilner, D.
Abstract: In order to look for signs of on-going planet formation in young disks, we carried out the first J-band polarized emission imaging of the Herbig Ae/Be stars HD 150193, HD 163296, and HD 169142 using the Gemini Planet Imager (GPI), along with new H band observations of HD 144432. We confirm the complex "double ring" structure for the nearly face-on system HD 169142 first seen in H-band, finding the outer ring to be substantially redder than the inner one in polarized intensity. Using radiative transfer modeling, we developed a physical model that explains the full spectral energy distribution (SED) and J- and H-band surface brightness profiles, suggesting that the differential color of the two rings could come from reddened starlight traversing the inner wall and may not require differences in grain properties. In addition, we clearly detect an elongated, off-center ring in HD 163296 (MWC 275), locating the scattering surface to be 18 AU above the midplane at a radial distance of 77 AU, co-spatial with a ring seen at 1.3mm by ALMA linked to the CO snow line. Lastly, we report a weak tentative detection of scattered light for HD 150193 (MWC 863) and a non-detection for HD 144432; the stellar companion known for each of these targets has likely disrupted the material in the outer disk of the primary star. For HD 163296 and HD 169142, the prominent outer rings we detect could be evidence for giant planet formation in the outer disk or a manifestation of large-scale dust growth processes possibly related to snow-line chemistry., Comment: Accepted Astrophysical Journal
Published: 2017
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40. The peculiar debris disk of HD 111520 as resolved by the Gemini Planet Imager

Author: Draper, ZH, Draper, ZH, Duchêne, G, Millar-Blanchaer, MA, Matthews, BC, Wang, JJ, Kalas, P, Graham, JR, Padgett, D, Ammons, SM, Bulger, J, Chen, C, Chilcote, JK, Doyon, R, Fitzgerald, MP, Follette, KB, Gerard, B, Greenbaum, AZ, Hibon, P, Hinkley, S, MacIntosh, B, Ingraham, P, Lafrenière, D, Marchis, F, Marois, C, Nielsen, EL, Oppenheimer, R, Patel, R, Patience, J, Perrin, M, Pueyo, L, Rajan, A, Rameau, J, Sivaramakrishnan, A, Vega, D, Ward-Duong, K, Wolff, SG, Draper, ZH, Draper, ZH, Duchêne, G, Millar-Blanchaer, MA, Matthews, BC, Wang, JJ, Kalas, P, Graham, JR, Padgett, D, Ammons, SM, Bulger, J, Chen, C, Chilcote, JK, Doyon, R, Fitzgerald, MP, Follette, KB, Gerard, B, Greenbaum, AZ, Hibon, P, Hinkley, S, MacIntosh, B, Ingraham, P, Lafrenière, D, Marchis, F, Marois, C, Nielsen, EL, Oppenheimer, R, Patel, R, Patience, J, Perrin, M, Pueyo, L, Rajan, A, Rameau, J, Sivaramakrishnan, A, Vega, D, Ward-Duong, K, and Wolff, SG
Abstract: Using the Gemini Planet Imager, we have resolved the circumstellar debris disk around HD 111520 at a projected range of ∼30-100 AU in both total and polarized H-band intensity. The disk is seen edge-on at a position angle of 165° along the spine of emission. A slight inclination and asymmetric warp are covariant and alter the interpretation of the observed disk emission. We employ three point-spread function subtraction methods to reduce the stellar glare and instrumental artifacts to confirm that there is a roughly 2:1 brightness asymmetry between the NW and SE extension. This specific feature makes HD 111520 the most extreme example of asymmetric debris disks observed in scattered light among similar highly inclined systems, such as HD 15115 and HD 106906. We further identify a tentative localized brightness enhancement and scale height enhancement associated with the disk at ∼40 AU away from the star on the SE extension. We also find that the fractional polarization rises from 10% to 40% from 0.″5 to 0.″8 from the star. The combination of large brightness asymmetry and symmetric polarization fraction leads us to believe that an azimuthal dust density variation is causing the observed asymmetry.
Published: 2016

41. Imaging an 80 au radius dust ring around the F5V star HD 157587

Author: Millar-Blanchaer, MA, Millar-Blanchaer, MA, Wang, JJ, Kalas, P, Graham, JR, Duchêne, G, Nielsen, EL, Perrin, M, Moon, DS, Padgett, D, Metchev, S, Ammons, SM, Bailey, VP, Barman, T, Bruzzone, S, Bulger, J, Chen, CH, Chilcote, J, Cotten, T, Rosa, RJD, Doyon, R, Draper, ZH, Esposito, TM, Fitzgerald, MP, Follette, KB, Gerard, BL, Greenbaum, AZ, Hibon, P, Hinkley, S, Hung, LW, Ingraham, P, Johnson-Groh, M, Konopacky, Q, Larkin, JE, MacIntosh, B, Maire, J, Marchis, F, Marley, MS, Marois, C, Matthews, BC, Oppenheimer, R, Palmer, D, Patience, J, Poyneer, L, Pueyo, L, Rajan, A, Rameau, J, Rantakyrö, FT, Savransky, D, Schneider, AC, Sivaramakrishnan, A, Song, I, Soummer, R, Thomas, S, Vega, D, Wallace, JK, Ward-Duong, K, Wiktorowicz, S, Wolff, S, Millar-Blanchaer, MA, Millar-Blanchaer, MA, Wang, JJ, Kalas, P, Graham, JR, Duchêne, G, Nielsen, EL, Perrin, M, Moon, DS, Padgett, D, Metchev, S, Ammons, SM, Bailey, VP, Barman, T, Bruzzone, S, Bulger, J, Chen, CH, Chilcote, J, Cotten, T, Rosa, RJD, Doyon, R, Draper, ZH, Esposito, TM, Fitzgerald, MP, Follette, KB, Gerard, BL, Greenbaum, AZ, Hibon, P, Hinkley, S, Hung, LW, Ingraham, P, Johnson-Groh, M, Konopacky, Q, Larkin, JE, MacIntosh, B, Maire, J, Marchis, F, Marley, MS, Marois, C, Matthews, BC, Oppenheimer, R, Palmer, D, Patience, J, Poyneer, L, Pueyo, L, Rajan, A, Rameau, J, Rantakyrö, FT, Savransky, D, Schneider, AC, Sivaramakrishnan, A, Song, I, Soummer, R, Thomas, S, Vega, D, Wallace, JK, Ward-Duong, K, Wiktorowicz, S, and Wolff, S
Abstract: We present H-band near-infrared polarimetric imaging observations of the F5V star HD 157587 obtained with the Gemini Planet Imager (GPI) that reveal the debris disk as a bright ring structure at a separation of ∼80-100 au. The new GPI data complement recent Hubble Space Telescope/STIS observations that show the disk extending out to over 500 au. The GPI image displays a strong asymmetry along the projected minor axis as well as a fainter asymmetry along the projected major axis. We associate the minor and major axis asymmetries with polarized forward scattering and a possible stellocentric offset, respectively. To constrain the disk geometry, we fit two separate disk models to the polarized image, each using a different scattering phase function. Both models favor a disk inclination of ∼70° and a 1.5 ± 0.6 au stellar offset in the plane of the sky along the projected major axis of the disk. We find that the stellar offset in the disk plane, perpendicular to the projected major axis is degenerate with the form of the scattering phase function and remains poorly constrained. The disk is not recovered in total intensity due in part to strong adaptive optics residuals, but we recover three point sources. Considering the system's proximity to the galactic plane and the point sources' positions relative to the disk, we consider it likely that they are background objects and unrelated to the disk's offset from the star.
Published: 2016

42. POINT SOURCE POLARIMETRY with the GEMINI PLANET IMAGER: SENSITIVITY CHARACTERIZATION with T5.5 DWARF COMPANION HD 19467 B

Author: Jensen-Clem, R, Jensen-Clem, R, Millar-Blanchaer, M, Mawet, D, Graham, JR, Wallace, JK, Macintosh, B, Hinkley, S, Wiktorowicz, SJ, Perrin, MD, Marley, MS, Fitzgerald, MP, Oppenheimer, R, Ammons, SM, Rantakyrö, FT, Marchis, F, Jensen-Clem, R, Jensen-Clem, R, Millar-Blanchaer, M, Mawet, D, Graham, JR, Wallace, JK, Macintosh, B, Hinkley, S, Wiktorowicz, SJ, Perrin, MD, Marley, MS, Fitzgerald, MP, Oppenheimer, R, Ammons, SM, Rantakyrö, FT, and Marchis, F
Abstract: Detecting polarized light from self-luminous exoplanets has the potential to provide key information about rotation, surface gravity, cloud grain size, and cloud coverage. While field brown dwarfs with detected polarized emission are common, no exoplanet or substellar companion has yet been detected in polarized light. With the advent of high contrast imaging spectro-polarimeters such as GPI and SPHERE, such a detection may now be possible with careful treatment of instrumental polarization. In this paper, we present 28 minutes of H-band GPI polarimetric observations of the benchmark T5.5 companion HD 19467 B. We detect no polarization signal from the target, and place an upper limit on the degree of linear polarization of pCL99.73% ≤ 2.4%. We discuss our results in the context of T dwarf cloud models and photometric variability.
Published: 2016

43. Cloudless atmospheres for L/T dwarfs and extra-solar giant planets

Author: Tremblin, P., Amundsen, D. S., Chabrier, G., Baraffe, I., Drummond, B., Hinkley, S., Mourier, P., Venot, O., Tremblin, P., Amundsen, D. S., Chabrier, G., Baraffe, I., Drummond, B., Hinkley, S., Mourier, P., and Venot, O.
Abstract: The admitted, conventional scenario to explain the complex spectral evolution of brown dwarfs (BD) since their first detections twenty years ago, has always been the key role played by micron-size condensates, called "dust" or "clouds", in their atmosphere. This scenario, however, faces major problems, in particular the J-band brightening and the resurgence of FeH absorption at the L to T transition, and a physical first-principle understanding of this transition is lacking. In this paper, we propose a new, completely different explanation for BD and extrasolar giant planet (EGP) spectral evolution, without the need to invoke clouds. We show that, due to the slowness of the CO/CH4 and N2/NH3 chemical reactions, brown dwarf (L and T, respectively) and EGP atmospheres are subject to a thermo-chemical instability similar in nature to the fingering or chemical convective instability present in Earth oceans and at the Earth core/mantle boundary. The induced small-scale turbulent energy transport reduces the temperature gradient in the atmosphere, explaining the observed increase in near infrared J-H and J-K colors of L dwarfs and hot EGPs, while a warming up of the deep atmosphere along the L to T transition, as the CO/CH4 instability vanishes, naturally solves the two aforementioned puzzles, and provides a physical explanation of the L to T transition. This new picture leads to a drastic revision of our understanding of BD and EGP atmospheres and their evolution., Comment: Accepted in ApJL, comments welcome
Published: 2016
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44. The peculiar debris disk of HD 111520 as resolved by the Gemini Planet Imager

Author: Draper, ZH, Draper, ZH, Duchêne, G, Millar-Blanchaer, MA, Matthews, BC, Wang, JJ, Kalas, P, Graham, JR, Padgett, D, Ammons, SM, Bulger, J, Chen, C, Chilcote, JK, Doyon, R, Fitzgerald, MP, Follette, KB, Gerard, B, Greenbaum, AZ, Hibon, P, Hinkley, S, MacIntosh, B, Ingraham, P, Lafrenière, D, Marchis, F, Marois, C, Nielsen, EL, Oppenheimer, R, Patel, R, Patience, J, Perrin, M, Pueyo, L, Rajan, A, Rameau, J, Sivaramakrishnan, A, Vega, D, Ward-Duong, K, Wolff, SG, Draper, ZH, Draper, ZH, Duchêne, G, Millar-Blanchaer, MA, Matthews, BC, Wang, JJ, Kalas, P, Graham, JR, Padgett, D, Ammons, SM, Bulger, J, Chen, C, Chilcote, JK, Doyon, R, Fitzgerald, MP, Follette, KB, Gerard, B, Greenbaum, AZ, Hibon, P, Hinkley, S, MacIntosh, B, Ingraham, P, Lafrenière, D, Marchis, F, Marois, C, Nielsen, EL, Oppenheimer, R, Patel, R, Patience, J, Perrin, M, Pueyo, L, Rajan, A, Rameau, J, Sivaramakrishnan, A, Vega, D, Ward-Duong, K, and Wolff, SG
Abstract: Using the Gemini Planet Imager, we have resolved the circumstellar debris disk around HD 111520 at a projected range of ∼30-100 AU in both total and polarized H-band intensity. The disk is seen edge-on at a position angle of 165° along the spine of emission. A slight inclination and asymmetric warp are covariant and alter the interpretation of the observed disk emission. We employ three point-spread function subtraction methods to reduce the stellar glare and instrumental artifacts to confirm that there is a roughly 2:1 brightness asymmetry between the NW and SE extension. This specific feature makes HD 111520 the most extreme example of asymmetric debris disks observed in scattered light among similar highly inclined systems, such as HD 15115 and HD 106906. We further identify a tentative localized brightness enhancement and scale height enhancement associated with the disk at ∼40 AU away from the star on the SE extension. We also find that the fractional polarization rises from 10% to 40% from 0.″5 to 0.″8 from the star. The combination of large brightness asymmetry and symmetric polarization fraction leads us to believe that an azimuthal dust density variation is causing the observed asymmetry.
Published: 2016

45. Imaging an 80 au radius dust ring around the F5V star HD 157587

Author: Millar-Blanchaer, MA, Millar-Blanchaer, MA, Wang, JJ, Kalas, P, Graham, JR, Duchêne, G, Nielsen, EL, Perrin, M, Moon, DS, Padgett, D, Metchev, S, Ammons, SM, Bailey, VP, Barman, T, Bruzzone, S, Bulger, J, Chen, CH, Chilcote, J, Cotten, T, Rosa, RJD, Doyon, R, Draper, ZH, Esposito, TM, Fitzgerald, MP, Follette, KB, Gerard, BL, Greenbaum, AZ, Hibon, P, Hinkley, S, Hung, LW, Ingraham, P, Johnson-Groh, M, Konopacky, Q, Larkin, JE, MacIntosh, B, Maire, J, Marchis, F, Marley, MS, Marois, C, Matthews, BC, Oppenheimer, R, Palmer, D, Patience, J, Poyneer, L, Pueyo, L, Rajan, A, Rameau, J, Rantakyrö, FT, Savransky, D, Schneider, AC, Sivaramakrishnan, A, Song, I, Soummer, R, Thomas, S, Vega, D, Wallace, JK, Ward-Duong, K, Wiktorowicz, S, Wolff, S, Millar-Blanchaer, MA, Millar-Blanchaer, MA, Wang, JJ, Kalas, P, Graham, JR, Duchêne, G, Nielsen, EL, Perrin, M, Moon, DS, Padgett, D, Metchev, S, Ammons, SM, Bailey, VP, Barman, T, Bruzzone, S, Bulger, J, Chen, CH, Chilcote, J, Cotten, T, Rosa, RJD, Doyon, R, Draper, ZH, Esposito, TM, Fitzgerald, MP, Follette, KB, Gerard, BL, Greenbaum, AZ, Hibon, P, Hinkley, S, Hung, LW, Ingraham, P, Johnson-Groh, M, Konopacky, Q, Larkin, JE, MacIntosh, B, Maire, J, Marchis, F, Marley, MS, Marois, C, Matthews, BC, Oppenheimer, R, Palmer, D, Patience, J, Poyneer, L, Pueyo, L, Rajan, A, Rameau, J, Rantakyrö, FT, Savransky, D, Schneider, AC, Sivaramakrishnan, A, Song, I, Soummer, R, Thomas, S, Vega, D, Wallace, JK, Ward-Duong, K, Wiktorowicz, S, and Wolff, S
Abstract: We present H-band near-infrared polarimetric imaging observations of the F5V star HD 157587 obtained with the Gemini Planet Imager (GPI) that reveal the debris disk as a bright ring structure at a separation of ∼80-100 au. The new GPI data complement recent Hubble Space Telescope/STIS observations that show the disk extending out to over 500 au. The GPI image displays a strong asymmetry along the projected minor axis as well as a fainter asymmetry along the projected major axis. We associate the minor and major axis asymmetries with polarized forward scattering and a possible stellocentric offset, respectively. To constrain the disk geometry, we fit two separate disk models to the polarized image, each using a different scattering phase function. Both models favor a disk inclination of ∼70° and a 1.5 ± 0.6 au stellar offset in the plane of the sky along the projected major axis of the disk. We find that the stellar offset in the disk plane, perpendicular to the projected major axis is degenerate with the form of the scattering phase function and remains poorly constrained. The disk is not recovered in total intensity due in part to strong adaptive optics residuals, but we recover three point sources. Considering the system's proximity to the galactic plane and the point sources' positions relative to the disk, we consider it likely that they are background objects and unrelated to the disk's offset from the star.
Published: 2016

46. POINT SOURCE POLARIMETRY with the GEMINI PLANET IMAGER: SENSITIVITY CHARACTERIZATION with T5.5 DWARF COMPANION HD 19467 B

Author: Jensen-Clem, R, Jensen-Clem, R, Millar-Blanchaer, M, Mawet, D, Graham, JR, Wallace, JK, Macintosh, B, Hinkley, S, Wiktorowicz, SJ, Perrin, MD, Marley, MS, Fitzgerald, MP, Oppenheimer, R, Ammons, SM, Rantakyrö, FT, Marchis, F, Jensen-Clem, R, Jensen-Clem, R, Millar-Blanchaer, M, Mawet, D, Graham, JR, Wallace, JK, Macintosh, B, Hinkley, S, Wiktorowicz, SJ, Perrin, MD, Marley, MS, Fitzgerald, MP, Oppenheimer, R, Ammons, SM, Rantakyrö, FT, and Marchis, F
Abstract: Detecting polarized light from self-luminous exoplanets has the potential to provide key information about rotation, surface gravity, cloud grain size, and cloud coverage. While field brown dwarfs with detected polarized emission are common, no exoplanet or substellar companion has yet been detected in polarized light. With the advent of high contrast imaging spectro-polarimeters such as GPI and SPHERE, such a detection may now be possible with careful treatment of instrumental polarization. In this paper, we present 28 minutes of H-band GPI polarimetric observations of the benchmark T5.5 companion HD 19467 B. We detect no polarization signal from the target, and place an upper limit on the degree of linear polarization of pCL99.73% ≤ 2.4%. We discuss our results in the context of T dwarf cloud models and photometric variability.
Published: 2016

47. Cloudless atmospheres for L/T dwarfs and extra-solar giant planets

Author: Tremblin, P., Amundsen, D. S., Chabrier, G., Baraffe, I., Drummond, B., Hinkley, S., Mourier, P., Venot, O., Tremblin, P., Amundsen, D. S., Chabrier, G., Baraffe, I., Drummond, B., Hinkley, S., Mourier, P., and Venot, O.
Abstract: The admitted, conventional scenario to explain the complex spectral evolution of brown dwarfs (BD) since their first detections twenty years ago, has always been the key role played by micron-size condensates, called "dust" or "clouds", in their atmosphere. This scenario, however, faces major problems, in particular the J-band brightening and the resurgence of FeH absorption at the L to T transition, and a physical first-principle understanding of this transition is lacking. In this paper, we propose a new, completely different explanation for BD and extrasolar giant planet (EGP) spectral evolution, without the need to invoke clouds. We show that, due to the slowness of the CO/CH4 and N2/NH3 chemical reactions, brown dwarf (L and T, respectively) and EGP atmospheres are subject to a thermo-chemical instability similar in nature to the fingering or chemical convective instability present in Earth oceans and at the Earth core/mantle boundary. The induced small-scale turbulent energy transport reduces the temperature gradient in the atmosphere, explaining the observed increase in near infrared J-H and J-K colors of L dwarfs and hot EGPs, while a warming up of the deep atmosphere along the L to T transition, as the CO/CH4 instability vanishes, naturally solves the two aforementioned puzzles, and provides a physical explanation of the L to T transition. This new picture leads to a drastic revision of our understanding of BD and EGP atmospheres and their evolution., Comment: Accepted in ApJL, comments welcome
Published: 2016
Full Text: View/download PDF

48. Direct imaging of an asymmetric debris disk in the HD 106906 planetary system

Author: Kalas, PG, Kalas, PG, Rajan, A, Wang, JJ, Millar-Blanchaer, MA, Duchene, G, Chen, C, Fitzgerald, MP, Dong, R, Graham, JR, Patience, J, Macintosh, B, Murray-Clay, R, Matthews, B, Rameau, J, Marois, C, Chilcote, J, Rosa, RJD, Doyon, R, Draper, ZH, Lawler, S, Ammons, SM, Arriaga, P, Bulger, J, Cotten, T, Follette, KB, Goodsell, S, Greenbaum, A, Hibon, P, Hinkley, S, Hung, LW, Ingraham, P, Konapacky, Q, Lafreniere, D, Larkin, JE, Long, D, Maire, J, Marchis, F, Metchev, S, Morzinski, KM, Nielsen, EL, Oppenheimer, R, Perrin, MD, Pueyo, L, Rantakyrö, FT, Ruffio, JB, Saddlemyer, L, Savransky, D, Schneider, AC, Sivaramakrishnan, A, Soummer, R, Song, I, Thomas, S, Vasisht, G, Ward-Duong, K, Wiktorowicz, SJ, Wolff, SG, Kalas, PG, Kalas, PG, Rajan, A, Wang, JJ, Millar-Blanchaer, MA, Duchene, G, Chen, C, Fitzgerald, MP, Dong, R, Graham, JR, Patience, J, Macintosh, B, Murray-Clay, R, Matthews, B, Rameau, J, Marois, C, Chilcote, J, Rosa, RJD, Doyon, R, Draper, ZH, Lawler, S, Ammons, SM, Arriaga, P, Bulger, J, Cotten, T, Follette, KB, Goodsell, S, Greenbaum, A, Hibon, P, Hinkley, S, Hung, LW, Ingraham, P, Konapacky, Q, Lafreniere, D, Larkin, JE, Long, D, Maire, J, Marchis, F, Metchev, S, Morzinski, KM, Nielsen, EL, Oppenheimer, R, Perrin, MD, Pueyo, L, Rantakyrö, FT, Ruffio, JB, Saddlemyer, L, Savransky, D, Schneider, AC, Sivaramakrishnan, A, Soummer, R, Song, I, Thomas, S, Vasisht, G, Ward-Duong, K, Wiktorowicz, SJ, and Wolff, SG
Abstract: We present the first scattered light detections of the HD 106906 debris disk using the Gemini/Gemini Planet Imager in the infrared and Hubble Space Telescope (HST)/Advanced Camera for Surveys in the optical. HD 106906 is a 13 Myr old F5V star in the Sco-Cen association, with a previously detected planet-mass candidate HD 106906b projected 650 AU from the host star. Our observations reveal a near edge-on debris disk that has a central cleared region with radius ∼50 AU, and an outer extent >500 AU. The HST data show that the outer regions are highly asymmetric, resembling the "needle" morphology seen for the HD 15115 debris disk. The planet candidate is oriented ∼21° away from the position angle of the primary's debris disk, strongly suggesting non-coplanarity with the system. We hypothesize that HD 106906b could be dynamically involved in the perturbation of the primary's disk, and investigate whether or not there is evidence for a circumplanetary dust disk or cloud that is either primordial or captured from the primary. We show that both the existing optical properties and near-infrared colors of HD 106906b are weakly consistent with this possibility, motivating future work to test for the observational signatures of dust surrounding the planet.
Published: 2015

49. Gemini planet imager observations of the au microscopii debris disk: Asymmetries within one arcsecond

Author: Wang, JJ, Wang, JJ, Graham, JR, Pueyo, L, Nielsen, EL, Millar-Blanchaer, M, Rosa, RJD, Kalas, P, Ammons, SM, Bulger, J, Cardwell, A, Chen, C, Chiang, E, Chilcote, JK, Doyon, R, Draper, ZH, Duchêne, G, Esposito, TM, Fitzgerald, MP, Goodsell, SJ, Greenbaum, AZ, Hartung, M, Hibon, P, Hinkley, S, Hung, LW, Ingraham, P, Larkin, JE, Macintosh, B, Maire, J, Marchis, F, Marois, C, Matthews, BC, Morzinski, KM, Oppenheimer, R, Patience, J, Perrin, MD, Rajan, A, Rantakyrö, FT, Sadakuni, N, Serio, A, Sivaramakrishnan, A, Soummer, R, Thomas, S, Ward-Duong, K, Wiktorowicz, SJ, Wolff, SG, Wang, JJ, Wang, JJ, Graham, JR, Pueyo, L, Nielsen, EL, Millar-Blanchaer, M, Rosa, RJD, Kalas, P, Ammons, SM, Bulger, J, Cardwell, A, Chen, C, Chiang, E, Chilcote, JK, Doyon, R, Draper, ZH, Duchêne, G, Esposito, TM, Fitzgerald, MP, Goodsell, SJ, Greenbaum, AZ, Hartung, M, Hibon, P, Hinkley, S, Hung, LW, Ingraham, P, Larkin, JE, Macintosh, B, Maire, J, Marchis, F, Marois, C, Matthews, BC, Morzinski, KM, Oppenheimer, R, Patience, J, Perrin, MD, Rajan, A, Rantakyrö, FT, Sadakuni, N, Serio, A, Sivaramakrishnan, A, Soummer, R, Thomas, S, Ward-Duong, K, Wiktorowicz, SJ, and Wolff, SG
Abstract: We present Gemini Planet Imager (GPI) observations of AU Microscopii, a young M dwarf with an edge-on, dusty debris disk. Integral field spectroscopy and broadband imaging polarimetry were obtained during the commissioning of GPI. In our broadband imaging polarimetry observations, we detect the disk only in total intensity and find asymmetries in the morphology of the disk between the southeast (SE) and northwest (NW) sides. The SE side of the disk exhibits a bump at 1″ (10 AU projected separation) that is three times more vertically extended and three times fainter in peak surface brightness than the NW side at similar separations. This part of the disk is also vertically offset by 69 ± 30 mas to the northeast at 1″ when compared to the established disk midplane and is consistent with prior Atacama Large Millimeter/submillimeter Array and Hubble Space Telescope/Space Telescope Imaging Spectrograph observations. We see hints that the SE bump might be a result of detecting a horizontal sliver feature above the main disk that could be the disk backside. Alternatively, when including the morphology of the NW side, where the disk midplane is offset in the opposite direction ∼50 mas between 0.″4 and 1.″2, the asymmetries suggest a warp-like feature. Using our integral field spectroscopy data to search for planets, we are 50% complete for ∼4 MJup planets at 4 AU. We detect a source, resolved only along the disk plane, that could either be a candidate planetary mass companion or a compact clump in the disk.
Published: 2015

50. Discovery and spectroscopy of the young jovian planet 51 Eri b with the Gemini Planet Imager.

Author: Macintosh, B, Macintosh, B, Graham, JR, Barman, T, De Rosa, RJ, Konopacky, Q, Marley, MS, Marois, C, Nielsen, EL, Pueyo, L, Rajan, A, Rameau, J, Saumon, D, Wang, JJ, Patience, J, Ammons, M, Arriaga, P, Artigau, E, Beckwith, S, Brewster, J, Bruzzone, S, Bulger, J, Burningham, B, Burrows, AS, Chen, C, Chiang, E, Chilcote, JK, Dawson, RI, Dong, R, Doyon, R, Draper, ZH, Duchêne, G, Esposito, TM, Fabrycky, D, Fitzgerald, MP, Follette, KB, Fortney, JJ, Gerard, B, Goodsell, S, Greenbaum, AZ, Hibon, P, Hinkley, S, Cotten, TH, Hung, L-W, Ingraham, P, Johnson-Groh, M, Kalas, P, Lafreniere, D, Larkin, JE, Lee, J, Line, M, Long, D, Maire, J, Marchis, F, Matthews, BC, Max, CE, Metchev, S, Millar-Blanchaer, MA, Mittal, T, Morley, CV, Morzinski, KM, Murray-Clay, R, Oppenheimer, R, Palmer, DW, Patel, R, Perrin, MD, Poyneer, LA, Rafikov, RR, Rantakyrö, FT, Rice, EL, Rojo, P, Rudy, AR, Ruffio, J-B, Ruiz, MT, Sadakuni, N, Saddlemyer, L, Salama, M, Savransky, D, Schneider, AC, Sivaramakrishnan, A, Song, I, Soummer, R, Thomas, S, Vasisht, G, Wallace, JK, Ward-Duong, K, Wiktorowicz, SJ, Wolff, SG, Zuckerman, B, Macintosh, B, Macintosh, B, Graham, JR, Barman, T, De Rosa, RJ, Konopacky, Q, Marley, MS, Marois, C, Nielsen, EL, Pueyo, L, Rajan, A, Rameau, J, Saumon, D, Wang, JJ, Patience, J, Ammons, M, Arriaga, P, Artigau, E, Beckwith, S, Brewster, J, Bruzzone, S, Bulger, J, Burningham, B, Burrows, AS, Chen, C, Chiang, E, Chilcote, JK, Dawson, RI, Dong, R, Doyon, R, Draper, ZH, Duchêne, G, Esposito, TM, Fabrycky, D, Fitzgerald, MP, Follette, KB, Fortney, JJ, Gerard, B, Goodsell, S, Greenbaum, AZ, Hibon, P, Hinkley, S, Cotten, TH, Hung, L-W, Ingraham, P, Johnson-Groh, M, Kalas, P, Lafreniere, D, Larkin, JE, Lee, J, Line, M, Long, D, Maire, J, Marchis, F, Matthews, BC, Max, CE, Metchev, S, Millar-Blanchaer, MA, Mittal, T, Morley, CV, Morzinski, KM, Murray-Clay, R, Oppenheimer, R, Palmer, DW, Patel, R, Perrin, MD, Poyneer, LA, Rafikov, RR, Rantakyrö, FT, Rice, EL, Rojo, P, Rudy, AR, Ruffio, J-B, Ruiz, MT, Sadakuni, N, Saddlemyer, L, Salama, M, Savransky, D, Schneider, AC, Sivaramakrishnan, A, Song, I, Soummer, R, Thomas, S, Vasisht, G, Wallace, JK, Ward-Duong, K, Wiktorowicz, SJ, Wolff, SG, and Zuckerman, B
Abstract: Directly detecting thermal emission from young extrasolar planets allows measurement of their atmospheric compositions and luminosities, which are influenced by their formation mechanisms. Using the Gemini Planet Imager, we discovered a planet orbiting the ~20-million-year-old star 51 Eridani at a projected separation of 13 astronomical units. Near-infrared observations show a spectrum with strong methane and water-vapor absorption. Modeling of the spectra and photometry yields a luminosity (normalized by the luminosity of the Sun) of 1.6 to 4.0 × 10(-6) and an effective temperature of 600 to 750 kelvin. For this age and luminosity, "hot-start" formation models indicate a mass twice that of Jupiter. This planet also has a sufficiently low luminosity to be consistent with the "cold-start" core-accretion process that may have formed Jupiter.
Published: 2015

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