Kavli Affiliate: Bruce Macintosh
| First 5 Authors: Brittany E. Miles, Beth A. Biller, Polychronis Patapis, Kadin Worthen, Emily Rickman
| Summary:
We present the highest fidelity spectrum to date of a planetary-mass object.
VHS 1256 b is a $<$20 M$_mathrm{Jup}$ widely separated ($sim$8arcsec, 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 textit{JWST}’s NIRSpec IFU and MIRI MRS
modes for coverage from 1 $mu$m to 20 $mu$m at resolutions of $sim$1,000 –
3,700. Water, methane, carbon monoxide, carbon dioxide, sodium, and potassium
are observed in several portions of the textit{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.
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