The JWST Early-release Science Program for Direct Observations of Exoplanetary Systems II: A 1 to 20 μm Spectrum of the Planetary-mass Companion VHS 1256–1257 b
Brittany Miles, Beth Biller, Polychronis Patapis, Kadin Worthen, Emily Rickman, Kielan K. W. Hoch, Andrew Skemer, Marshall D. Perrin, Niall Whiteford, Christine Chen, B. A. Sargent, Sagnick Mukherjee, Caroline Morley, Sarah E. Moran, M. Bonnefoy, Simon Petrus, Aarynn L. Carter, Élodie Choquet, Sasha Hinkley, Kimberly Ward-Duong, Jarron Leisenring, Maxwell A. Millar‐Blanchaer, Laurent Pueyo, Shrishmoy Ray, Steph Sallum, Karl R. Stapelfeldt, Jordan Stone, Jason Wang, Olivier Absil, William O. Balmer, A. Boccaletti, M. Bonavita, Mark Booth, Brendan P. Bowler, G. Chauvin, Valentin Christiaens, Thayne Currie, Camilla Danielski, Jonathan J. Fortney, J. H. Girard, C. A. Grady, Alexandra Z. Greenbaum, Thomas Henning, Dean C. Hines, M. Janson, Paul Kalas, Jens Kammerer, Grant M. Kennedy, Matthew A. Kenworthy, P. Kervella, Pierre-Olivier Lagage, Ben W. P. Lew, Michael C. Liu, Bruce Macintosh, Sebastián Marino, Mark S. Marley, Christian Marois, Elisabeth C. Matthews, Brenda C. Matthews, Dimitri Mawet, Michael W. McElwain, Stanimir Metchev, Michael R. Meyer, P. Mollière, E. Pantin, A. Quirrenbach, Isabel Rebollido, Bin Ren, Glenn Schneider, Malavika Vasist, M. C. Wyatt, Yifan Zhou, Zackery Briesemeister, Marta L. Bryan, Per Calissendorff, F. Cantalloube, 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, Anne- Marie Lagrange, Kellen Lawson, C. Lazzoni, Pengyu Liu, Jorge Llop-Sayson, James P. Lloyd, Raquel A. Martinez, Johan Mazoyer, Sascha P. Quanz, Jéa Adams Redai, M. Samland, Joshua E. Schlieder
Abstract
Abstract We present the highest fidelity spectrum to date of a planetary-mass object. VHS 1256 b is a <20 M Jup widely separated (∼8″, a = 150 au), young, planetary-mass companion that shares photometric colors and spectroscopic features with the directly imaged exoplanets HR 8799c, 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 to 20 μ m at resolutions of ∼1000–3700. 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.