55 Cancri

Name

55 Cancri (pronounced /ˈkæŋkraɪ/, abbreviated 55 Cnc) is a binary star located around 41 light-years away in the constellation Cancer. It has the Bayer designation Rho1 Cancri. The system contains a yellow dwarf star (55 Cancri A) similar to our Sun and a red dwarf (55 Cancri B). The two components are separated by over 1000 times the distance from the Earth to the Sun.
As of 2007, five extrasolar planets are known in orbit around 55 Cancri A. Four of the planets are comparable to Jupiter in mass, while the innermost planet has a mass similar to that of Neptune. The 55 Cancri system was the first known five-planet extrasolar planetary system.

55 Cancri A is ranked 63rd in the list of top 100 target stars for the NASA Terrestrial Planet Finder mission.[1].

Distance and visibility

The 55 Cancri system is located fairly close to our solar system: the Hipparcos astrometry satellite measured the parallax of 55 Cancri A as 79.80 milliarcseconds, corresponding to a distance of 12.5 parsecs.[2] 55 Cancri A has an apparent magnitude of 5.95, making it visible through binoculars. It is just visible to the naked eye under very dark skies. The red dwarf 55 Cancri B is of the 13th magnitude and only visible through a telescope.