HD 80606 b atmosphere and rotation

Study of the atmospheric response of HD 80606 b around periastron.

de Wit et al. (2016) "Direct Measure of Radiative and Dynamical Properties of an Exoplanet Atmosphere"
http://iopscience.iop.org/article/10.3847/2041-8205/820/2/L33/meta

The planetary rotation period is determined to be 93⁺⁸⁵_-35 hours, while the predicted pseudo-synchronous rotation period is 39.9 hours (Hut 1981 model) or 28 hours (Ivanov & Papaloizou 2007 model). The radiative timescale is about 4 hours, and heat transport to the dark side of the planet is inefficient.

The amount of thermal emission through the bulk of the orbit suggests either substantial cloud coverage of marginal thermal emission. Constraint on tidal Q factor in the latter case suggests the orbit would be stable for billions of years, i.e. not a proto-hot Jupiter.

News article in Astronomy Now here.

And here it is on arXiv.

Direct Measure of Radiative and Dynamical Properties of an Exoplanet Atmosphere
http://arxiv.org/abs/1606.01105