Alien planet HD 187123b. Artwork of the extrasolar planet HD 187123b in orbit around its parent star, HD 187123. This star lies in the constellation Cygnus. The orbital period of this planet is just over 3 days, and it orbits just 6.3 million kilometres from its star. It is thought to be a Jupiter-type gas giant planet, with a mass 170 times that of Earth. Several groups of sunspots (dark) can be seen on the surface of the star.