brown dwarfs; planets and satellites: atmospheres; techniques: high angular resolution; planet-disk interactions
Abstract :
[en] Context. The substellar companion HD 206893b has recently been discovered by direct imaging of its disc-bearing host star with the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument. <BR /> Aims: We investigate the atypical properties of the companion, which has the reddest near-infrared colours among all known substellar objects, either orbiting a star or isolated, and we provide a comprehensive characterisation of the host star-disc-companion system. <BR /> Methods: We conducted a follow-up of the companion with adaptive optics imaging and spectro-imaging with SPHERE, and a multi-instrument follow-up of its host star. We obtain a R = 30 spectrum from 0.95 to 1.64 μm of the companion and additional photometry at 2.11 and 2.25 μm. We carried out extensive atmosphere model fitting for the companions and the host star in order to derive their age, mass, and metallicity. <BR /> Results: We found no additional companion in the system in spite of exquisite observing conditions resulting in sensitivity to 6 M[SUB]Jup[/SUB] (2 M[SUB]Jup[/SUB]) at 0.5'' for an age of 300 Myr (50 Myr). We detect orbital motion over more than one year and characterise the possible Keplerian orbits. We constrain the age of the system to a minimum of 50 Myr and a maximum of 700 Myr, and determine that the host-star metallicity is nearly solar. The comparison of the companion spectrum and photometry to model atmospheres indicates that the companion is an extremely dusty late L dwarf, with an intermediate gravity (log g 4.5-5.0) which is compatible with the independent age estimate of the system. <BR /> Conclusions: Though our best fit corresponds to a brown dwarf of 15-30 M[SUB]Jup[/SUB] aged 100-300 Myr, our analysis is also compatible with a range of masses and ages going from a 50 Myr 12 M[SUB]Jup[/SUB] planetary-mass object to a 50 M[SUB]Jup[/SUB] Hyades-age brown dwarf. Even though this companion is extremely red, we note that it is more probable that it has an intermediate gravity rather than the very low gravity that is often associated with very red L dwarfs. We also find that the detected companion cannot shape the observed outer debris disc, hinting that one or several additional planetary mass objects in the system might be necessary to explain the position of the disc inner edge. Based on observations made with ESO Telescopes at the Paranal Observatory under Programs ID 097.C-0865(D) (SPHERE GTO, SHINE Program) and Program ID: 082.A-9007(A) (FEROS) 098.C-0739(A), 192.C-0224(C) (HARPS). This work has made use of the SPHERE Data Centre.
Research center :
STAR - Space sciences, Technologies and Astrophysics Research - ULiège
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Delorme, Philippe; Univ. Grenoble Alpes, CNRS, IPAG, 38000, Grenoble, France
Schmidt, Tobias; 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, Mickaël; Univ. Grenoble Alpes, CNRS, IPAG, 38000, Grenoble, France
Ginski, Christian; Leiden Observatory, Niels Bohrweg 2, 2333 CA, Leiden, The Netherlands ; Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
Charnay, Benjamin D.; 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
Milli, J.; European Southern Observatory (ESO), Alonso de Córdova 3107, Vitacura, Casilla 19001, Santiago, Chile
Schlieder, J. E.; Max-Planck-Institute for Astronomy, Koenigsthul 17, 69117, Heidelberg, Germany ; Exoplanets and Stellar Astrophysics Laboratory, Code 667, NASA-Goddard Space Flight Center, Greenbelt, MD, 20771, USA
Rodet, L.; Univ. Grenoble Alpes, CNRS, IPAG, 38000, Grenoble, France
Lagrange, A.-M.; Univ. Grenoble Alpes, CNRS, IPAG, 38000, Grenoble, France
Absil, Olivier ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS)
Vigan, A.; Aix Marseille Univ., CNRS, LAM, Laboratoire d'Astrophysique de Marseille, Marseille, France
Galicher, R.; 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
Hagelberg, J.; Univ. Grenoble Alpes, CNRS, IPAG, 38000, Grenoble, France
Bonavita, M.; Institute for Astronomy, The University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ, UK
Lavie, B.; Geneva Observatory, University of Geneva, Chemin des Maillettes 51, 1290, Versoix, Switzerland ; Physikalisches Institut, University of Bern, Sidlerstrasse 5, 3012, Bern, Switzerland
Zurlo, A.; Aix Marseille Univ., CNRS, LAM, Laboratoire d'Astrophysique de Marseille, Marseille, France ; Núcleo de Astronomía, Facultad de Ingeniería, Universidad Diego Portales, Av. Ejercito 441, Santiago, Chile
Olofsson, J.; Max-Planck-Institute for Astronomy, Koenigsthul 17, 69117, Heidelberg, Germany ; Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Av. Gran Bretaña 1111, Playa Ancha, Valparaíso, Chile
Boccaletti, A.; 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
Cantalloube, F.; Max-Planck-Institute for Astronomy, Koenigsthul 17, 69117, Heidelberg, Germany
Mouillet, D.; Univ. Grenoble Alpes, CNRS, IPAG, 38000, Grenoble, France
Chauvin, G.; Univ. Grenoble Alpes, CNRS, IPAG, 38000, Grenoble, France
Hambsch, F.-J.; Remote Observatory Atacama Desert (ROAD), Vereniging Voor Sterrenkunde (VVS), Oude Bleken 12, 2400, Mol, Belgium
Langlois, M.; CRAL, UMR 5574, CNRS, Université Lyon 1, 9 Avenue Charles André, 69561, Saint Genis Laval Cedex, France ; Aix Marseille Univ., CNRS, LAM, Laboratoire d'Astrophysique de Marseille, Marseille, France
Udry, S.; Geneva Observatory, University of Geneva, Chemin des Maillettes 51, 1290, Versoix, Switzerland
Henning, T.; Max-Planck-Institute for Astronomy, Koenigsthul 17, 69117, Heidelberg, Germany
Beuzit, J.-L.; Univ. Grenoble Alpes, CNRS, IPAG, 38000, Grenoble, France
Mordasini, C.; Physikalisches Institut, University of Bern, Sidlerstrasse 5, 3012, Bern, Switzerland
Lucas, P.; Centre for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire, Hatfield, AL10 9AB, UK
Marocco, F.; Centre for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire, Hatfield, AL10 9AB, UK
Biller, B.; Institute for Astronomy, University of Edinburgh, Blackford Hill View, Edinburgh, EH9 3HJ, UK
Carson, J.; Max-Planck-Institute for Astronomy, Koenigsthul 17, 69117, Heidelberg, Germany ; Department of Physics & Astronomy, College of Charleston, 58 Coming Street, Charleston, SC, 29424, USA
Cheetham, A.; Geneva Observatory, University of Geneva, Chemin des Maillettes 51, 1290, Versoix, Switzerland
Pavlov, A.; Max-Planck-Institute for Astronomy, Koenigsthul 17, 69117, Heidelberg, Germany
Petit, C.; ONERA, 29 Avenue de la Division Leclerc, 92322 Châtillon Cedex, France
Rouan, D.; 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
Roelfsema, R.; NOVA Optical-Infrared Instrumentation Group at ASTRON, Oude Hoogeveensedijk 4, 7991PD, Dwingeloo, The Netherlands
Wildi, F.; Geneva Observatory, University of Geneva, Chemin des Maillettes 51, 1290, Versoix, Switzerland)
