Issue |
A&A
Volume 605, September 2017
|
|
---|---|---|
Article Number | L9 | |
Number of page(s) | 9 | |
Section | Letters | |
DOI | https://doi.org/10.1051/0004-6361/201731152 | |
Published online | 18 September 2017 |
Discovery of a warm, dusty giant planet around HIP 65426⋆,⋆⋆
1 Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
e-mail: gael.chauvin@univ-grenoble-alpes.fr
2 Unidad Mixta Internacional Franco-Chilena de Astronomía, CNRS/INSU UMI 3386 and Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile
3 INAF–Osservatorio Astronomico di Padova, Vicolo dell’ Osservatorio 5, 35122, Padova, Italy
4 Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 13388 Marseille, France
5 CRAL, UMR 5574, CNRS, Université de Lyon, École Normale Supérieure de Lyon, 46 Allée d’Italie, 69364 Lyon Cedex 07, France
6 Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
7 Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093 Zurich, Switzerland
8 The University of Michigan, Ann Arbor, MI 48109, USA
9 Geneva Observatory, University of Geneva, Chemin des Mailettes 51, 1290 Versoix, Switzerland
10 SUPA, Institute for Astronomy, The University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ, UK
11 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
12 Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Av. Gran Bretaña 1111, Valparaíso, Chile
13 Université Côte d’Azur, OCA, CNRS, Lagrange, France
14 Department of Astronomy, Stockholm University, AlbaNova University Center, 106 91 Stockholm, Sweden
15 Physikalisches Institut, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland
16 INAF – Catania Astrophysical Observatory, via S. Sofia, 78 95123 Catania, Italy
17 Núcleo de Astronomía, Facultad de Ingeniería, Universidad Diego Portales, Av. Ejercito 441, Santiago, Chile
18 Anton Pannekoek Institute for Astronomy, Science Park 904, 1098 XH Amsterdam, The Netherlands
19 INAF–Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
20 INAF–Osservatorio Astronomico di Capodimonte, SalitaMoiariello 16, 80131 Napoli, Italy
21 ONERA (Office National d’Études et de Recherches Aérospatiales), BP 72, 92322 Châtillon, France
22 European Southern Observatory (ESO), Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
23 NOVA Optical Infrared Instrumentation Group, Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The Netherlands
24 INAF–Osservatorio Astronomico di Roma, via di Frascati 33, 00040 Monte Porzio Catone, Italy
25 Department of Astrophysics, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH, UK
26 European Southern Observatory (ESO), Alonso de Córdova 3107, Vitacura, Casilla 19001, Santiago, Chile
27 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
28 School of Earth & Space Exploration, Arizona State University, Tempe AZ 85287, USA
29 Ural Federal University, Yekaterinburg 620002, Russia
30 CNRS, CFHT, 65-1238 Mamalahoa Hwy, Kamuela HI 96743, USA
31 Exoplanets and Stellar Astrophysics Laboratory, NASA Goddard Space Flight Center, 8800 Greenbelt Rd., Greenbelt, MD 20771, USA
Received: 10 May 2017
Accepted: 13 June 2017
Aims. The SHINE program is a high-contrast near-infrared survey of 600 young, nearby stars aimed at searching for and characterizing new planetary systems using VLT/SPHERE’s unprecedented high-contrast and high-angular-resolution imaging capabilities. It is also intended to place statistical constraints on the rate, mass and orbital distributions of the giant planet population at large orbits as a function of the stellar host mass and age to test planet-formation theories.
Methods. We used the IRDIS dual-band imager and the IFS integral field spectrograph of SPHERE to acquire high-contrast coronagraphic differential near-infrared images and spectra of the young A2 star HIP 65426. It is a member of the ~17 Myr old Lower Centaurus-Crux association.
Results. At a separation of 830 mas (92 au projected) from the star, we detect a faint red companion. Multi-epoch observations confirm that it shares common proper motion with HIP 65426. Spectro-photometric measurements extracted with IFS and IRDIS between 0.95 and 2.2 μm indicate a warm, dusty atmosphere characteristic of young low-surface-gravity L5-L7 dwarfs. Hot-start evolutionary models predict a luminosity consistent with a 6–12 MJup, Teff = 1300–1600 K and R = 1.5 ± 0.1 RJup giant planet. Finally, the comparison with Exo-REM and PHOENIX BT-Settl synthetic atmosphere models gives consistent effective temperatures but with slightly higher surface gravity solutions of log (g) = 4.0–5.0 with smaller radii (1.0–1.3 RJup).
Conclusions. Given its physical and spectral properties, HIP 65426 b occupies a rather unique placement in terms of age, mass, and spectral-type among the currently known imaged planets. It represents a particularly interesting case to study the presence of clouds as a function of particle size, composition, and location in the atmosphere, to search for signatures of non-equilibrium chemistry, and finally to test the theory of planet formation and evolution.
Key words: instrumentation: adaptive optics / instrumentation: high angular resolution / methods: observational / planets and satellites: atmospheres / planets and satellites: formation
Based on observations collected at La Silla and Paranal Observatory, ESO (Chile) Program ID: 097.C-0865 and 098.C-0209 (SPHERE).
The planet spectrum is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/605/L9
© ESO, 2017
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