In-depth direct imaging and spectroscopic characterization of the young Solar System analog HD 95086

¹ Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
e-mail: celia.desgrange@univ-grenoble-alpes.fr
² Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
³ Unidad Mixta Internacional Franco-Chilena de Astronomía, CNRS/INSU UMI 3386 and Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile
⁴ Space sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, 19 Allée du Six Août, 4000 Liège, Belgium
⁵ Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France
⁶ Univ. Paris-Saclay, ENS de Paris-Saclay, Paris-Saclay, France
⁷ Pixyl, 5 Avenue du Grand Sablon, 38700 La Tronche, France
⁸ Academia Sinica Institute of Astronomy and Astrophysics, 11F Astronomy-Mathematics Building, NTU/AS campus, No. 1, Section 4, Roosevelt Rd., Taipei 10617, Taiwan
⁹ School of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
¹⁰ INAF – Osservatorio Astronomico di Padova, Vicolo dell’ Osservatorio 5, 35122 Padova, Italy
¹¹ LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, 5 place Jules Janssen, 92195 Meudon, France
¹² CRAL, UMR 5574, CNRS, Université de Lyon, École Normale Supérieure de Lyon, 46 Allée d’Italie, 69364 Lyon Cedex 07, France
¹³ Institute for Particle Physics and Astrophysics, ETH Zürich, Wolfgang-Pauli-Strasse 27, 8093, Zürich, Switzerland
¹⁴ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
¹⁵ Cornell Center for Astrophysics and Planetary Science, Department of Astronomy, Cornell University, Ithaca, NY 14853, USA
¹⁶ Institutionen för astronomi, Stockholms Universitet, Stockholm, Sweden
¹⁷ European Southern Observatory, Alonso de Cordova 3107, Casilla 19001 Vitacura, Santiago, Chile
¹⁸ SUPA, Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
¹⁹ Centre for Exoplanet Science, University of Edinburgh, Edinburgh, UK
²⁰ DOTA, ONERA, Université Paris Saclay, 91123 Palaiseau, France
²¹ Geneva Observatory, University of Geneva, 51 ch. Pegasi, 1290 Versoix, Switzerland
²² Dipartimento di Fisica a Astronomia “G. Galilei”, Università di Padova, Via Marzolo, 8, 35121 Padova, Italy
²³ Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Bd de l’Observatoire, CS 34229, 06304 Nice cedex 4, France
²⁴ INAF – Osservatorio Astrofísico di Catania, via Santa Sofia, 78 Catania, Italy
²⁵ European Southern Observatory (ESO), Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
²⁶ Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
²⁷ Núcleo de Astronomía, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejercito 441, Santiago, Chile
²⁸ Escuela de Ingeniería Industrial, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejercito 441, Santiago, Chile

Received: 12 January 2022
Accepted: 25 April 2022

Abstract

Context. HD 95086 is a young nearby Solar System analog hosting a giant exoplanet orbiting at 57 au from the star between an inner and outer debris belt. The existence of additional planets has been suggested as the mechanism that maintains the broad cavity between the two belts.

Aims. We present a dedicated monitoring of HD 95086 with the VLT/SPHERE instrument to refine the orbital and atmospheric properties of HD 95086 b, and to search for additional planets in this system.

Methods. SPHERE observations, spread over ten epochs from 2015 to 2019 and including five new datasets, were used. Combined with archival observations, from VLT/NaCo (2012-2013) and Gemini/GPI (2013-2016), the extended set of astrometric measurements allowed us to refine the orbital properties of HD 95086 b. We also investigated the spectral properties and the presence of a circumplanetary disk around HD 95086 b by using the special fitting tool exploring the diversity of several atmospheric models. In addition, we improved our detection limits in order to search for a putative planet c via the K-Stacker algorithm.

Results. We extracted for the first time the JH low-resolution spectrum of HD 95086 b by stacking the six best epochs, and confirm its very red spectral energy distribution. Combined with additional datasets from GPI and NaCo, our analysis indicates that this very red color can be explained by the presence of a circumplanetary disk around planet b, with a range of high-temperature solutions (1400–1600 K) and significant extinction (A_v ≳ 10 mag), or by a super-solar metallicity atmosphere with lower temperatures (800–300 K), and small to medium amount of extinction (A_v ≲ 10 mag). We do not find any robust candidates for planet c, but give updated constraints on its potential mass and location.