Orbiting a binary

M. Bonavita (1, 2) , V. d'Orazi (1, 3) , D. Mesa (1) , C. Fontanive (4) , S. Desidera (1) , S. Messina (1, 5) , S. Daemgen (6) , R. Gratton (1) , Arthur Vigan (7) , M. Bonnefoy (8) , A. Zurlo (1, 9) , J. Antichi (10) , H. Avenhaus (11) , A. Baruffolo (1) , J. L. Baudino (12) , J. L. Beuzit (8) , A. Boccaletti (13) , P. Bruno (1) , T. Buey (13) , M. Carbillet (14) , E. Cascone (15) , G. Chauvin (8) , R. U. Claudi (1) , V. de Caprio (15) , D. Fantinel (1) , G. Farisato (1) , M. Feldt (16) , R. Galicher (13) , E. Giro (1) , C. Gry (7) , J. Hagelberg (8) , S. Incorvaia (17) , M. Janson (18) , M. Jaquet (7) , A. M. Lagrange (8) , M. Langlois (7) , J. Lannier (8) , H. Le Coroller (7) , L. Lessio (1) , R. Ligi (7) , A. L. Maire (19) , M. Meyer (20) , F. Menard (21, 8) , C. Perrot (13) , S. Peretti (22) , C. Petit (23) , J. Ramos (16) , A. Roux (8) , B. Salasnich (1) , G. Salter (7) , M. Samland (16) , S. Scuderi (5) , J. Schlieder (16, 24) , M. Surez (23) , M. Turatto (1) , L. Weber (25)

1 OAPD - INAF - Osservatorio Astronomico di Padova
2 SUPA, Institute for Astronomy
3 Monash University [Melbourne]
4 IfA - Institute for Astronomy [Edinburgh]
5 OACT - INAF - Osservatorio Astrofisico di Catania
6 Institute of Astronomy [ETH Zürich]
7 LAM - Laboratoire d'Astrophysique de Marseille
8 IPAG - Institut de Planétologie et d'Astrophysique de Grenoble
9 UDP - Universidad Diego Portales [Santiago - Chili]
10 OAA - INAF - Osservatorio Astrofisico di Arcetri
11 ETH Zürich - Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich]
12 University of Oxford
13 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics
14 OCA - Observatoire de la Côte d'Azur
15 OAC - INAF - Osservatorio Astronomico di Capodimonte
16 MPIA - Max-Planck-Institut für Astronomie
17 OAM - INAF - Osservatorio Astronomico di Milano
18 Department of Astronomy
19 Max Planck Institute for Radio Astronomy
20 DPHN - Département de Physique Nucléaire (ex SPhN)
21 LFCA - Laboratoire Franco-Chilien d'Astronomie
22 ObsGE - Observatoire Astronomique de l'Université de Genève
23 ONERA
24 GSFC - NASA Goddard Space Flight Center
25 CREATIS - Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé

Aims. In this paper we present the results of the SPHERE observation of the HD 284149 system, aimed at a more detailed characterisation of both the primary and its brown dwarf companion.Methods. We observed HD 284149 in the near-infrared with SPHERE, using the imaging mode (IRDIS+IFS) and the long-slit spectroscopy mode (IRDIS-LSS). The data were reduced using the dedicated SPHERE pipeline, and algorithms such as PCA and TLOCI were applied to reduce the speckle pattern. Results. The IFS images revealed a previously unknown low-mass (~0.16 M⊙) stellar companion (HD 294149 B) at ~0.1′′, compatible with previously observed radial velocity differences, as well as proper motion differences between Gaia and Tycho-2 measurements. The known brown dwarf companion (HD 284149 b) is clearly visible in the IRDIS images. This allowed us to refine both its photometry and astrometry. The analysis of the medium resolution IRDIS long slit spectra also allowed a refinement of temperature and spectral type estimates. A full reassessment of the age and distance of the system was also performed, leading to more precise values of both mass and semi-major axis.Conclusions. As a result of this study, HD 284149 ABb therefore becomes the latest addition to the (short) list of brown dwarfs on wide circumbinary orbits, providing new evidence to support recent claims that object in such configuration occur with a similar frequency to wide companions to single stars.

Mots clés: stars: individual: HD 284149; brown dwarfs; binaries: visual; stars: rotation; techniques: high angular resolution

Domaines: Astrophysique [astro-ph]

M. Bonavita, V. d'Orazi, D. Mesa, C. Fontanive, S. Desidera, et al.. Orbiting a binary: SPHERE characterisation of the HD 284149 system. Astronomy and Astrophysics - A&A, 2017, 608, pp.A106. ⟨10.1051/0004-6361/201731003⟩. ⟨hal-01764685⟩