Limits on Clouds and Hazes for the Trappist-1 Planets
Limits on Clouds and Hazes for the Trappist-1 Planets by S.E. Moran, and CSI Member Nikole K. Lewis and colleagues, email: email@example.com
and f to match the HST data. For TRAPPIST-1 g, we cannot rule out a clear hydrogen-rich atmosphere. We modeled the effects an opaque cloud deck and substantial heavy element content have on the transmission spectra using the updated mass estimates. We determine that hydrogen-rich atmospheres with high altitude clouds, at pressures of 12 mbar and lower, are consistent with the HST observations for TRAPPIST-1 d and e. For TRAPPIST-1 f and g, we cannot rule out clear hydrogen-rich cases to high confidence. We demonstrate that metallicities of at least 60 × solar with tropospheric (0.1 bar) clouds are in agreement with observations. Additionally, we provide estimates of the precision necessary for future observations to disentangle degeneracies in cloud top pressure and metallicity. For TRAPPIST-1 e and f, for example, 20 ppm precision is needed to distinguish between a clear atmosphere and an atmosphere with a thick cloud layer at 0.1 bar across a wide range (1 × to 1000 × solar) of metallicity. Our results suggest secondary, volatile-rich atmospheres for the outer TRAPPIST-1 planets d, e, and f.