A super-Earth is revealed
An international research group has, on the initiative of astrophysicist Michaël Gillon from Liege, observed the emission of a super-Earth for the first time, that is to say its own light. This news opens the way to a more in-depth study of planets which are relatively small.
55 Cancri e
Thanks to previous observations of the radial velocity of the star and the transit of the planet, it has been established that 55 Cancri e has a radius two times greater than the Earth and a mass that is eight times greater. This allowed astrophysicists to get an approximate idea of its density and therefore its most probable composition. Michaël Gillon explains, “55 Cancri e is an object that is composed mainly of rock, with some more volatile components. Hypothetically, we are inclined to think that there is an external layer of water ice in the supercritical state, given the very high temperature on the surface and the immense pressure due to gravity. We could find other volatile components there such as methane, for example. The only place where water could be found in the gaseous state is on the surface, forming a secondary atmosphere surrounding the planet. The mix between rock and ice would suggest an object resembling what we imagine the cores of Neptune and Uranus to be, without their gas envelope composed mainly of hydrogen and helium.”
(1) Demory B.-O., Gillon M., Seager S., Benneke B., Deming D. & Jackson B., Detection of Thermal Emission from a Super-Earth, The Astrophysical Journal Letters, 2012.