Published 2024 | Version v1
Journal article

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

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.
Briesemeister, Zackery W.
Bryan, Marta L.
Calissendorff, Per
Cantalloube, Faustine
Chen, Christine H.
Choquet, Elodie
Christiaens, Valentin
Cugno, Gabriele
Currie, Thayne
Danielski, Camilla
de Furio, Matthew
Dupuy, Trent J.
Factor, Samuel M.
Faherty, Jacqueline K.
Fitzgerald, Michael P.
Fortney, Jonathan J.
Franson, Kyle
Girard, Julien H.
Grady, Carol A.
Henning, Thomas
Hines, Dean C.
Hood, Callie E.
Howe, Alex R.
Kalas, Paul
Kammerer, Jens
Kennedy, Grant M.
Kenworthy, Matthew A.
Kervella, Pierre
Kim, Minjae
Kitzmann, Daniel
Kraus, Adam L.
Kuzuhara, Masayuki
Lagage, Pierre-Olivier
Lagrange, Anne-Marie
Lawson, Kellen
Lazzoni, Cecilia
Leisenring, Jarron M.
Lew, Ben W. P.
Liu, Michael C.
Liu, Pengyu
Llop-Sayson, Jorge
Lloyd, James P.
Macintosh, Bruce
Mâlin, Mathilde
Manjavacas, Elena
Marino, Sebastián
Marley, Mark S.
Marois, Christian
Martinez, Raquel A.
Matthews, Elisabeth C.
Matthews, Brenda C.
Mawet, Dimitri
Mazoyer, Johan
Mcelwain, Michael W.
Metchev, Stanimir
Meyer, Michael R.
Millar-Blanchaer, Maxwell A.
Mollière, Paul
Moran, Sarah E.
Mukherjee, Sagnick
Pantin, Eric
Perrin, Marshall D.
Pueyo, Laurent
Quanz, Sascha P.
Quirrenbach, Andreas
Ray, Shrishmoy
Rebollido, Isabel
Adams Redai, Jea
Ren, Bin B.
Rickman, Emily
Sallum, Steph
Samland, Matthias
Sargent, Benjamin
Schlieder, Joshua E.
Stapelfeldt, Karl R.
Tamura, Motohide
Tan, Xianyu
Theissen, Christopher A.
Uyama, Taichi
Vasist, Malavika
Vigan, Arthur
Wagner, Kevin
Ward-Duong, Kimberly
Wolff, Schuyler G.
Worthen, Kadin
Wyatt, Mark C.
Ygouf, Marie
Zurlo, Alice
Zhang, Xi
Zhang, Keming
Zhang, Zhoujian
Zhou, Yifan

Description

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.

Abstract

International audience

Additional details

Created:
October 9, 2024
Modified:
October 9, 2024