Published January 31, 2023
| Version v1
Journal article
X-SHYNE: X-shooter spectra of young exoplanet analogs: I. A medium-resolution 0.65-2.5 μ m one-shot spectrum of VHS 1256-1257 b
Contributors
Others:
- Joseph Louis LAGRANGE (LAGRANGE) ; Université Nice Sophia Antipolis (1965 - 2019) (UNS) ; COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur ; COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
- Institut de Planétologie et d'Astrophysique de Grenoble (IPAG) ; Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ) ; Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France
- Maison de la Simulation (MDLS) ; Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut National de Recherche en Informatique et en Automatique (Inria)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
- Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA) ; Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris ; Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
- Deutsche Forschungsgemeinschaft, DFG: MA 9185/1; Agence Nationale de la Recherche, ANR: ANR-14-CE33-0018, ANR-20-CE31-0012; Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, SNF: 200021_204847; Agencia Nacional de Investigación y Desarrollo, ANID: NCN19_171
- We would like to thank the staff of ESO VLT for their support at the telescope at Paranal and La Silla, and the preparation of the observation at Garching. This publication made use of the SIMBAD and VizieR database operated at the CDS, Strasbourg, France. This work has made use of data from the European Space Agency (ESA) mission Gaia ( https://www.cosmos.esa.int/gaia ), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consor576u tium ). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. We acknowledge support in France from the French National Research Agency (ANR) through project grants ANR-14-CE33-0018 and ANR-20-CE31-0012. S.-P. acknowledges the support of ANID, – Millennium Science Initiative Program – NCN19_171. G-DM acknowledges the support of the DFG priority program SPP 1992 "Exploring the Diversity of Extrasolar Planets" (MA 9185/1) and from the Swiss National Science Foundation under grant 200021_204847 "PlanetsInTime". Parts of this work have been carried out within the framework of the NCCR PlanetS supported by the Swiss National Science Foundation.
- ANR-14-CE33-0018,GIPSE,Exploration des planetes géantes extrasolaires(2014)
- ANR-20-CE31-0012,FRAME,Détection et Caractérisation des Exoplanètes en Formation(2020)
Description
We present simultaneous 0.65-2.5 m medium resolution (3300 R 8100) VLT/X-shooter spectra of the relatively young (150-300 Myr) low-mass (19 5MJup) L-T transition object VHS 1256-1257 b, a known spectroscopic analog of HR8799d. The companion is a prime target for the JWST Early Release Science (ERS) and one of the highest-Amplitude variable brown dwarfs known to date. We compare the spectrum to the custom grids of cloudless ATMO models, exploring the atmospheric composition with the Bayesian inference tool ForMoSA. We also reanalyze low-resolution HST/WFC3 1.10-1.67 m spectra at minimum and maximum variability to contextualize the X-shooter data interpretation. The models reproduce the slope and most molecular absorption from 1.10 to 2.48 m self-consistently, but they fail to provide a radius and a surface gravity consistent with evolutionary model predictions. They do not reproduce the optical spectrum and the depth of the K I doublets in the J band consistently. We derived Te = 138054 K, log(g) = 3.970.48 dex, [M/H] = 0.210.29, and C/O 0.63. Our inversion of the HST/WFC3 spectra suggests a relative change of 27+6-5 K of the disk-integrated Te correlated with the near-infrared brightness. Our data anchor the characterization of that object in the near-infrared and could be used jointly to the ERS mid-infrared data to provide the most detailed characterization of an ultracool dwarf to date.
Abstract
International audienceAdditional details
Identifiers
- URL
- https://hal.science/hal-04122780
- URN
- urn:oai:HAL:hal-04122780v1