55 Cancri c
55 Cancri c is an extrasolar planet orbiting the component A of the binary system 55 Cancri. Due to its high mass is assumed that it is a gas planet. It is seen from its star from the third known planet of its planetary system.
As the majority of exoplanets this one was also using the radial velocity method after analysis of observational data collected from 1989 to 2002 at the Lick Observatory, discovered. At the time of discovery was already known that 55 Cancri a planet, namely 55 Cancri b possesses. Planet c and d were published by Geoffrey Marcy and R. Paul Butler in June 2002. There was initially some doubts whether it really is a planet, since the star has a very similar rotation period of 42 days, which could mimic a planet with this orbital period. Through further observations these doubts could be dispelled so that 55 Cancri c deemed to be confirmed.
The planet has on the model with five major planets in orbit around 55 Cancri A is only slightly eccentric orbit of 0.086. He may possess a 1:3 orbital resonance with the more inner planet b. One revolution is completed every 44.34 Earth days. The planet orbits its star at an average distance ( semi-major axis) of about 0.24 Astronomical Units. He is him thus closer than Mercury to the sun.
55 Cancri c has a minimum mass of 0.169 Jupiter masses or almost 54 Earth masses. In the currently accepted Systeminklination of 53 °, but has yet to be confirmed, it would be with 0.21 Jupiter masses significantly more massive. It is assumed that a gas planet without solid surface.