Article (Périodiques scientifiques)
A dusty benchmark brown dwarf near the ice line of HD 72946
Maire, Anne-Lise; Baudino, J.-L.; Desidera, S. et al.
2019In Astronomy and Astrophysics, 633, p. 2
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Mots-clés :
brown dwarfs; methods: data analysis; stars: individual: HD 72946; planets and satellites: dynamical evolution and stability; techniques: high angular resolution; techniques: image processing
Résumé :
[en] Context. HD 72946 is a bright and nearby solar-type star hosting a low- mass companion at long period (P ̃ 16 yr) detected with the radial velocity (RV) method. The companion has a minimum mass of 60.4 ± 2.2 M[SUB]J[/SUB] and might be a brown dwarf. Its expected semi-major axis of ̃243 mas makes it a suitable target for further characterization with high-contrast imaging, in particular to measure its inclination, mass, and spectrum and thus definitely establish its substellar nature. <BR /> Aims: We aim to further characterize the orbit, atmosphere, and physical nature of HD 72946B. <BR /> Methods: We present high-contrast imaging data in the near-infrared with the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument. We also use proper motion measurements of the star from HIPPARCOS and Gaia. <BR /> Results: The SPHERE data reveal a point source with a contrast of ̃9 mag at a projected separation of ̃235 mas. No other point sources are detected in the field of view. By jointly fitting the RV, imaging, and proper motion data, we constrain all the orbital parameters of HD 72946B and assess a dynamical mass of 72.4 ± 1.6 M[SUB]J[/SUB] and a semi-major axis of 6.456.45[SUP]+0.08[/SUP][SUB]-0.07[/SUB] au. Empirical comparison of its SPHERE spectrum to template dwarfs indicates a spectral type of L5.0 ± 1.5. The J-H3 color is close to the expectations of the DUSTY models and suggests a cloudy atmosphere. Comparison with atmospheric models of the spectrophotometry suggests an effective temperature of ̃1700 K. The bolometric luminosity (log(L/L[SUB]☉[/SUB]) = -4.11 ± 0.10 dex) and dynamical mass of HD 72946B are more compatible with evolutionary models for an age range of ̃0.9-3 Gyr. The formation mechanism of the companion is currently unclear as the object appears slightly away from the bulk of model predictions. HD 72946B is currently the closest benchmark brown dwarf companion to a solar-type star with imaging, RV, and proper motion measurements. <P />Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme 0102.C-0781.
Centre/Unité de recherche :
STAR - Space sciences, Technologies and Astrophysics Research - ULiège
Disciplines :
Aérospatiale, astronomie & astrophysique
Auteur, co-auteur :
Maire, Anne-Lise ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > PSILab
Baudino, J.-L.;  Department of Physics, University of Oxford, Oxford, UK
Desidera, S.;  INAF-Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122, Padova, Italy
Messina, S.;  INAF Catania Astrophysical Observatory, Via S. Sofia 78, 95123, Catania, Italy
Brandner, W.;  Max-Planck-Institut für Astronomie, Königstuhl 17, 69117, Heidelberg, Germany
Godoy, N.;  Instituto de Física y Astronomía, Facultad de Ciencias, Univ. de Valparaíso, Av. Gran Bretaña 1111, Playa Ancha, Valparaíso, Chile ; Núcleo Milenio Formación Planetaria - NPF, Univ. de Valparaíso, Av. Gran Bretaña 1111, Playa Ancha, Valparaíso, Chile
Cantalloube, F.;  Max-Planck-Institut für Astronomie, Königstuhl 17, 69117, Heidelberg, Germany
Galicher, Raphaël;  LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, 5 Place Jules Janssen, 92195, Meudon, France
Bonnefoy, M.;  Univ. Grenoble Alpes, CNRS, IPAG, 38000, Grenoble, France
Hagelberg, J.;  Geneva Observatory, University of Geneva, Chemin des Maillettes 51, 1290, Versoix, Switzerland
Olofsson, J.;  Instituto de Física y Astronomía, Facultad de Ciencias, Univ. de Valparaíso, Av. Gran Bretaña 1111, Playa Ancha, Valparaíso, Chile ; Núcleo Milenio Formación Planetaria - NPF, Univ. de Valparaíso, Av. Gran Bretaña 1111, Playa Ancha, Valparaíso, Chile
Absil, Olivier  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > PSILab
Chauvin, G.;  Univ. Grenoble Alpes, CNRS, IPAG, 38000, Grenoble, France ; Unidad Mixta Internacional Franco-Chilena de Astronomía CNRS/INSU UMI 3386 and Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile
Henning, T.;  Max-Planck-Institut für Astronomie, Königstuhl 17, 69117, Heidelberg, Germany
Langlois, M.;  CRAL, UMR 5574, CNRS/ENS-Lyon/Université Lyon 1, 9 Av. Ch. André, 69561, Saint-Genis-Laval, France)
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Langue du document :
Anglais
Titre :
A dusty benchmark brown dwarf near the ice line of HD 72946
Date de publication/diffusion :
23 décembre 2019
Titre du périodique :
Astronomy and Astrophysics
ISSN :
0004-6361
eISSN :
1432-0746
Maison d'édition :
EDP Sciences, Les Ulis, France
Volume/Tome :
633
Pagination :
L2
Peer reviewed :
Peer reviewed vérifié par ORBi
Intitulé du projet de recherche :
TIHE
Organisme subsidiant :
F.R.S.-FNRS - Fonds de la Recherche Scientifique
Disponible sur ORBi :
depuis le 17 janvier 2020

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