The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems II: A 1 to 20 Micron Spectrum of the Planetary-Mass Companion VHS 1256-1257 b

We present the highest fidelity spectrum to date of a planetary-mass object. VHS 1256 b is a <20 MJup widely separated (∼8\arcsec, a = 150 au), young, planetary-mass companion that shares photometric colors and spectroscopic features with the directly imaged exoplanets HR 8799 c, d, and e.

As an L-to-T transition object, VHS 1256 b exists along the region of the color-magnitude diagram where substellar atmospheres transition from cloudy to clear. We observed VHS 1256~b with JWST’s NIRSpec IFU and MIRI MRS modes for coverage from 1 μm to 20 μm at resolutions of ∼1,000 – 3,700. Water, methane, carbon monoxide, carbon dioxide, sodium, and potassium are observed in several portions of the JWST spectrum based on comparisons from template brown dwarf spectra, molecular opacities, and atmospheric models.

The spectral shape of VHS 1256 b is influenced by disequilibrium chemistry and clouds. We directly detect silicate clouds, the first such detection reported for a planetary-mass companion.

Brittany E. Miles, Beth A. Biller, Polychronis Patapis, Kadin Worthen, Emily Rickman, Kielan K. W. Hoch, Andrew Skemer, Marshall D. Perrin, Niall Whiteford, Christine H. Chen, Sagnick Mukherjee, Caroline V. Morley, Sarah E. Moran, Mickael Bonnefoy, Simon Petrus, Aarynn L. Carter, Elodie Choquet, Sasha Hinkley, Kimberly Ward-Duong, Jarron M. Leisenring, Maxwell A. Millar-Blanchaer, Laurent Pueyo, Shrishmoy Ray, Karl R. Stapelfeldt, Jordan M. Stone, Jason J. Wang, Olivier Absil, William O. Balmer, Anthony Boccaletti, Mariangela Bonavita, Mark Booth, Brendan P. Bowler, Gael Chauvin, Valentin Christiaens, Thayne Currie, Camilla Danielski, Jonathan J. Fortney, Julien H. Girard, Alexandra Z. Greenbaum, Thomas Henning, Dean C. Hines, Markus Janson, Paul Kalas, Jens Kammerer, Matthew A. Kenworthy, Pierre Kervella, Pierre-Olivier Lagage, Ben W. P. Lew, Michael C. Liu, Bruce Macintosh, Sebastian Marino, Mark S. Marley, Christian Marois, Elisabeth C. Matthews, Brenda C. Matthews, Dimitri Mawet, Michael W. McElwain, Stanimir Metchev, Michael R. Meyer, Paul Molliere, Eric Pantin, Andreas Quirrenbachm Isabel Rebollido, Bin B. Ren, Malavika Vasist, Mark C. Wyatt, Yifan Zhou, Zackery W. Briesemeister, Marta L. Bryan, Per Calissendorff, Faustine Catalloube, Gabriele Cugno, Matthew De Furio, Trent J. Dupuy, Samuel M. Factor, Jacqueline K. Faherty, Michael P. Fitzgerald, Kyle Franson, Eileen C. Gonzales, Callie E. Hood, Alex R. Howe, Adam L. Kraus, Masayuki Kuzuhara, Kellen Lawson, Cecilia Lazzoni, Pengyu Liu, Jorge Llop-Sayson, James P. Lloyd, Raquel A. Martinez, Johan Mazoyer, Sascha P. Quanz, Jea Adams Redai, Matthias Samland, Joshua E. Schlieder, Motohide Tamura, Xianyu Tan, Taichi Uyama, Arthur Vigan, Johanna M. Vos, Kevin Wagner, Schuyler G. Wolff et al. (3 additional authors not shown)

Comments: Accepted ApJL Iterations of spectra reduced by the ERS team are hosted at this link: this https URL
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2209.00620 [astro-ph.EP] (or arXiv:2209.00620v2 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2209.00620
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Submission history
From: Brittany Miles
[v1] Thu, 1 Sep 2022 17:33:18 UTC (5,168 KB)
[v2] Sat, 11 Feb 2023 01:05:38 UTC (4,509 KB)
https://arxiv.org/abs/2209.00620

Astrobiology, Astrochemistry