The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems. V. Do Self-consistent Atmospheric Models Represent JWST Spectra? A Showcase with VHS 1256-1257 b

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

https://doi.org/10.3847/2041-8213/ad3e7c

ISSN

20418205

Creative Commons License

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

Rights

©2024 The Authors

Version

Version of Record

Recommended Citation

Petrus, Simon; Whiteford, Niall; Patapis, Polychronis; Biller, Beth A.; Skemer, Andrew; Hinkley, Sasha; Suárez, Genaro; Palma-Bifani, Paulina; Morley, Caroline V.; Tremblin, Pascal; Charnay, Benjamin; Vos, Johanna M.; Wang, Jason J.; Stone, Jordan M.; Bonnefoy, Mickaël; Chauvin, Gaël; Miles, Brittany E.; Carter, Aarynn L.; Lueber, Anna; Helling, Christiane; Sutlieff, Ben J.; Janson, Markus; Gonzales, Eileen C.; Hoch, Kielan K.W.; Absil, Olivier; Balmer, William O.; Boccaletti, Anthony; Bonavita, Mariangela; Booth, Mark; Bowler, Brendan P.; al, et; and Ward-Duong, Kimberly, "The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems. V. Do Self-consistent Atmospheric Models Represent JWST Spectra? A Showcase with VHS 1256-1257 b" (2024). Astronomy: Faculty Publications, Smith College, Northampton, MA.
https://scholarworks.smith.edu/ast_facpubs/140