Authors

Simon Petrus, Universidad de Valparaiso
Niall Whiteford, American Museum of Natural History
Polychronis Patapis, ETH Zürich
Beth A. Biller, University of Edinburgh, Institute for Astronomy
Andrew Skemer, University of California, Santa Cruz
Sasha Hinkley, University of Exeter
Genaro Suárez, American Museum of Natural History
Paulina Palma-Bifani, Laboratoire Joseph-Louis Lagrange
Caroline V. Morley, The University of Texas at Austin
Pascal Tremblin, Commissariat a l'Energie Atomique et aux Energies Alternatives
Benjamin Charnay, L'Observatoire de Paris
Johanna M. Vos, American Museum of Natural History
Jason J. Wang, Northwestern University
Jordan M. Stone, U.S. Naval Research Laboratory
Mickaël Bonnefoy, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG)
Gaël Chauvin, Laboratoire Joseph-Louis Lagrange
Brittany E. Miles, University of California, Santa Cruz
Aarynn L. Carter, University of California, Santa Cruz
Anna Lueber, Ludwig-Maximilians-Universität München
Christiane Helling, Institut fur Weltraumforschung
Ben J. Sutlieff, University of Edinburgh, Institute for Astronomy
Markus Janson, Stockholms universitet
Eileen C. Gonzales, San Francisco State University
Kielan K.W. Hoch, Space Telescope Science Institute
Olivier Absil, Université de Liège
William O. Balmer, Space Telescope Science Institute
Anthony Boccaletti, L'Observatoire de Paris
Mariangela Bonavita, The Open University
Mark Booth, Royal Observatory
Brendan P. Bowler, The University of Texas at Austin
et al, Various Institutions
Kimberly Ward-Duong, Smith CollegeFollow

Author ORCID Identifier

Kimberly Ward-Duong: 0000-0002-4479-8291

Document Type

Article

Publication Date

5-1-2024

Publication Title

Astrophysical Journal Letters

Abstract

The unprecedented medium-resolution (R λ ∼ 1500-3500) near- and mid-infrared (1-18 μm) spectrum provided by JWST for the young (140 ± 20 Myr) low-mass (12-20 M Jup) L-T transition (L7) companion VHS 1256 b gives access to a catalog of molecular absorptions. In this study, we present a comprehensive analysis of this data set utilizing a forward-modeling approach applying our Bayesian framework, ForMoSA. We explore five distinct atmospheric models to assess their performance in estimating key atmospheric parameters: T eff, log(g), [M/H], C/O, γ, f sed, and R. Our findings reveal that each parameter’s estimate is significantly influenced by factors such as the wavelength range considered and the model chosen for the fit. This is attributed to systematic errors in the models and their challenges in accurately replicating the complex atmospheric structure of VHS 1256 b, notably the complexity of its clouds and dust distribution. To propagate the impact of these systematic uncertainties on our atmospheric property estimates, we introduce innovative fitting methodologies based on independent fits performed on different spectral windows. We finally derived a T eff consistent with the spectral type of the target, considering its young age, which is confirmed by our estimate of log(g). Despite the exceptional data quality, attaining robust estimates for chemical abundances [M/H] and C/O, often employed as indicators of formation history, remains challenging. Nevertheless, the pioneering case of JWST’s data for VHS 1256 b has paved the way for future acquisitions of substellar spectra that will be systematically analyzed to directly compare the properties of these objects and correct the systematics in the models.

Volume

966

Issue

1

DOI

10.3847/2041-8213/ad3e7c

ISSN

20418205

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Rights

©2024 The Authors

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