VLTI/GRAVITY Observations and Characterization of the Brown Dwarf Companion HD 72946 B
Creators
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Balmer, William O.1, 2
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Pueyo, Laurent2
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Stolker, Tomas3
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Reggiani, Henrique4
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Maire, A.-L.5, 6
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Lacour, S.7, 8
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Mollière, P.6
- Nowak, M.9
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Sing, D.1
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Pourré, N.10
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Blunt, S.11
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Wang, J. J.12
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Rickman, E.2
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Kammerer, J.2
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Henning, Th.6
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Ward-Duong, K.13
- Abuter, R.8
- Amorim, A.14
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Asensio-Torres, R.6
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Benisty, M.10
- Berger, J.-P.10
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Beust, H.10
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Boccaletti, A.7
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Bohn, A.3
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Bonnefoy, M.10
- Bonnet, H.8
- Bourdarot, G.10, 15
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Brandner, W.6
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Cantalloube, F.16
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Caselli, P.15
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Charnay, B.7
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Chauvin, G.10
- Chavez, A.12
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Choquet, E.16
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Christiaens, V.17
- Clénet, Y.7
- Coudé du Foresto, V.7
- Cridland, A.3
- Dembet, R.8
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Dexter, J.18
- Drescher, A.15
- Duvert, G.10
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Eckart, A.19, 20
- Eisenhauer, F.15
- Gao, F.21
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Garcia, P.14, 22
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Garcia Lopez, R.6, 23
- Gendron, E.7
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Genzel, R.15
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Gillessen, S.15
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Girard, J. H.2
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Haubois, X.8
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Heißel, G.7
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Hinkley, S.24
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Hippler, S.6
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Horrobin, M.19
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Houllé, M.16
- Hubert, Z.10
- Jocou, L.10
- Keppler, M.6
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Kervella, P.7
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Kreidberg, L.6
- Lagrange, A.-M.7, 10
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Lapeyrère, V.7
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Le Bouquin, J.-B.10
- Léna, P.7
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Lutz, D.15
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Monnier, J. D.25
- Mouillet, D.10
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Nasedkin, E.6
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Ott, T.15
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Otten, G. P. P. L.26
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Paladini, C.8
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Paumard, T.7
- Perraut, K.10
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Perrin, G.7
- Pfuhl, O.8
- Rameau, J.10
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Rodet, L.27
- Rousset, G.7
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Rustamkulov, Z.1
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Shangguan, J.15
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Shimizu, T.15
- Stadler, J.15
- Straub, O.15
- Straubmeier, C.19
- Sturm, E.15
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Tacconi, L. J.15
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van Dishoeck, E. F.3, 15
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Vigan, A.16
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Vincent, F.7
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von Fellenberg, S. D.15
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Widmann, F.15
- Wieprecht, E.15
- Wiezorrek, E.15
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Winterhalder, T.8
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Woillez, J.8
- Yazici, S.15
- Young, A.15
- The ExoGRAVITY Collaboration
- The GRAVITY Collaboration
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1.
Johns Hopkins University
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2.
Space Telescope Science Institute
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3.
Leiden University
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4.
Carnegie Observatories
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5.
University of Liège
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6.
Max Planck Institute for Astronomy
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7.
Laboratory of Space Studies and Instrumentation in Astrophysics
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8.
European Southern Observatory
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9.
University of Cambridge
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10.
Institut de Planétologie et d'Astrophysique de Grenoble
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11.
California Institute of Technology
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12.
Northwestern University
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13.
Smith College
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14.
University of Lisbon
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15.
Max Planck Institute for Extraterrestrial Physics
- 16. Aix-Marseille Université, CNRS, CNES, LAM, Marseille, France
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17.
Monash University
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18.
University of Colorado Boulder
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19.
University of Cologne
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20.
Max Planck Institute for Radio Astronomy
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21.
Universität Hamburg
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22.
University of Porto
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23.
University College Dublin
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24.
University of Exeter
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25.
University of Michigan–Ann Arbor
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26.
Institute of Astronomy and Astrophysics, Academia Sinica
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27.
Cornell University
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 a nearby, solar-type star. We achieve ∼100 μas 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 MB = 69.5 ± 0.5 MJup assuming a strong prior on the host star mass MA = 0.97 ± 0.01 M⊙ 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 of 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. Independently of the cloud prescription and prior assumptions, we find agreement within ±2σ between the C/O of the host (0.52 ± 0.05) and brown dwarf (0.43–0.63), as expected from a molecular cloud collapse formation scenario, but our retrieved metallicities are implausibly high (0.6–0.8) in light of the 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.
Copyright and License
© 2023. The Author(s). Published by the American Astronomical Society.
Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Acknowledgement
W.O.B. would like to thank Jacob Hamer for his input regarding the age estimates of the HD 72946 system, and Sagnick Mukherjee for helpful discussions regarding clouds. We thank the anonymous referee for the helpful review. The authors sincerely thank the Paranal Observatory astronomers and local staff for their tremendous support in completing these observations.
Based on observations collected at the European Southern Observatory under ESO programme(s) 1104.C-0651(B), 1103.B-0626(D).
T.S. acknowledges support from the Netherlands Organisation for Scientific Research (NWO) through grant VI.Veni.202.230.
This work used the Dutch national e-infrastructure with the support of the SURF Cooperative using grant No. EINF-1620.
S.L. acknowledges the support of the French Agence Nationale de la Recherche (ANR), under grant ANR-21-CE31-0017 (project ExoVLTI).
This work is based on spectral data retrieved from the ELODIE archive at Observatoire de Haute-Provence (OHP), available at http://atlas.obs-hp.fr/elodie. It is also based on data retrieved from the SOPHIE archive at OHP, available at http://atlas.obs-hp.fr/sophie.
This research has made use of the VizieR catalog access tool, CDS, Strasbourg, France (DOI:10.26093/cds/vizier).
This research has made use of the Jean-Marie Mariotti Center Aspro service.
This publication makes use of data products from 2MASS, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation.
This work has made use of data from the European Space Agency mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC; https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.
W.O.B. acknowledges that the Johns Hopkins University (JHU) occupies the unceded land of the Piscataway people, and acknowledges the Piscataway community, their elders both past and present, and future generations. JHU (http://web.archive.org/web/20220816104243/http://trujhu.org/index.php/about-us/land-acknowledgement/) was founded on and presides over the exclusions and erasures of many people, a fact no less true for being contentious, and one that bears repeating even in long acknowledgment sections.
W.O.B. graciously acknowledges their cat, Morgoth, for her "encouragement."
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Additional details
Related works
- Is new version of
- Discussion Paper: arXiv:2309.04403 (arXiv)
- Is supplemented by
- Dataset: 10.26093/cds/vizier (DOI)
Funding
- Dutch Research Council
- VI.Veni.202.230
- Dutch Research Council
- EINF-1620
- Agence Nationale de la Recherche
- ANR-21-CE31-0017
- National Aeronautics and Space Administration
- National Science Foundation
Dates
- Accepted
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2023-09-05Accepted
- Available
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2023-10-12Published