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GJ 367b is a dark, hot, airless sub-Earth by Zhang, Michael; Hu, Renyu; Inglis, Julie; Dai, Fei; Bean, Jacob L.; Knutson, Heather A.; Lam, Kristine; Goffo, Elisa; Gandolfi, Davide is a scholarly article available to read on EtoBox.

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We present the mid-infrared (5-12 $\mu$m) phase curve of GJ 367b observed by the Mid-Infrared Instrument (MIRI) on the James Webb Space Telescope (JWST). GJ 367b is a hot (T_eq=1370 K), extremely dense (10.2 +- 1.3 g/cm^3) sub-Earth orbiting a M dwarf on a 0.32 d orbit. We measure an eclipse depth of 79 +- 4 ppm, a nightside planet-to-star flux ratio of 4 +- 8 ppm, and a relative phase amplitude of 0.97 +- 0.10 -- all fully consistent with a zero-albedo planet with no heat recirculation. Su ch a scenario is also consistent with the phase offset of 11 +- 5 degrees East to within 2.2$\sigma$. The emission spectrum is likewise consistent with a blackbody with no heat redistribution and a low albedo of A_B ~ 0.1, with the exception of one anomalous wavelength bin that we attribute to unexplained systematics. The emission spectrum puts few constraints on the surface composition, but rules out a CO2 atmosphere >~ 1 bar, an outgassed atmosphere >~10 mbar (under heavily reducing conditions), or an outgassed atmosphere >~0.01 mbar (under heavily oxidizing conditions). The lack of day-night heat recirculation implies that 1 bar atmospheres are ruled out for a wide range of compositions, whil

Author

Zhang, Michael; Hu, Renyu; Inglis, Julie; Dai, Fei; Bean, Jacob L.; Knutson, Heather A.; Lam, Kristine; Goffo, Elisa; Gandolfi, Davide

Published

2024

Language

EN