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
This work is licensed under a Creative Commons Attribution 4.0 International License.
Rights
©2024 The Authors
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
Comments
Archived as published.