Hot SuperEarth Gliese 1214b is Cloudy

An LBT view of the atmosphere of GJ1214b

Authors:

Nascimbeni et al

Abstract:

The atmospheric composition and vertical structure of the super-Earth GJ1214b has been questioned since its discovery in 2009. Recent studies point towards the presence of high-altitude clouds masking the lower layers. Anyway, some data points, gathered at different times and facilities, do not fit well into this picture, probably because of a combination of stellar activity and systematic errors. We observed two transits of GJ1214b with the LBC dual-channel camera at the Large Binocular Telescope. For the first time, we measured the relative planetary radius k=Rp/R⋆ at blue and red optical wavelengths simultaneously (B+R), thus constraining the presence of Rayleigh scattering on GJ1214b after correcting for stellar activity effects. To the same purpose, a long-term photometric follow-up of the host star was carried out with WiFSIP@STELLA, revealing a rotational period significantly longer than that previously reported. Our new unbiased estimates of k yield a flat transmission spectra extending to shorter wavelengths, thus confirming the "cloudy atmosphere" scenario for GJ1214b.