CoRoT-8b light and RV curves

We analyzed two complementary data sets: the photometric transit curve of CoRoT-8b as measured by CoRoT and the radial velocity curve of CoRoT-8 as measured by the HARPS spectrometer. We find that CoRoT-8b is on a circular orbit with a semi-major axis of 0.063+/-0.001AU.

It has a radius of 0.57+/-0.02RJ, a mass of 0.22+/-0.03MJ, and therefore a mean density 1.6+/-0.1g/cm^3^. With 67% of the size of Saturn and 72% of its mass, CoRoT-8b has a density comparable to that of Neptune (1.76g/cm^3^). We estimate its content in heavy elements to be 47-63 Earth masses, and the mass of its hydrogen-helium envelope to be 7-23 Earth masses.