Parviainen H. et al. (2014) reported the discovery of a massive high-density planet on a close-in 3.58 day orbit around a 4.2 billion-year-old Sun-like star. The planet has been identified as CoRoT-27b. Like Jupiter, CoRoT-27b is a gas-giant. It was detected by the CoRoT space telescope using the transit method, in which a planet periodically transits its host star and blocks a small fraction of the star’s light. CoRoT-27b weighs in at 10.39 ± 0.55 Jupiter-mass and has 1.01 ± 0.04 times the radius of Jupiter. This gives CoRoT-27b a mean density of 12.6 times the density of water, which is more than twice the mean density of Earth and almost 10 times the mean density of Jupiter.
Like Jupiter, CoRoT-27b is a gaseous planet comprised primarily of hydrogen and helium. The structure and composition of CoRoT-27b can be inferred from two models. For the first model, the planet is assumed to be made of a central rocky core surrounded by an extensive hydrogen-helium envelope. The first model is consistent with a heavy element mass fraction of 0.11, representing a core mass of 366 Earth-masses. For the second model, a central rocky core is absent and the heavy elements are present throughout the hydrogen-helium envelope. The second model is consistent with a heavy element mass fraction of 0.07, representing a heavy element mass of 219 Earth-masses.
Given its high mass, gravity on the surface of CoRoT-27b is 27 times the surface gravity on Earth. Technically, CoRoT-27b does not have a surface since it is gaseous throughout, right down to a central rocky core, if one is present. Being so near its host star, the equilibrium temperature on CoRoT-27b is estimated to be 1500 ± 130 K. The discovery of CoRoT-27b is an important addition to a scarcely populated class of massive close-in planets.
The host star CoRoT 27 has an apparent magnitude of 15.5, with an absolute magnitude of 25.00. It is 1.05 times more massive and 1.08 times larger compared to our sun. The surface temperature is 5900 K and it has a spectral type of G2. In this planetary system, the extrasolar planet CoRoT 27 b orbits around the star CoRoT 27 at an orbital distance of 0.0476.