55 Cnc: A Sun-Like Star and Its Five Known Planets

55 Cnc is a G8V star located 41 light-years away, making it a Sun-like main-sequence dwarf. Its reported mass is 0.96 solar masses and its radius 0.93 solar radii, both smaller than the Sun's. The star's temperature of 5240 K is cooler than the Sun's, and its age is 9.5 billion years. Five planets are known to orbit this host.

55 Cnc b was discovered in 1996 by the radial velocity method, which detects the wobble a planet's gravity induces in its star. Its minimum mass is 276 Earth masses, and it completes an orbit every 14.7 days. 55 Cnc c, found in 2004, has a minimum mass of 56.6 Earth masses and an orbital period of 44.4 days. 55 Cnc f, discovered in 2007, has a minimum mass of 48.5 Earth masses and a year of 261 days. The minimum masses of 55 Cnc b, 55 Cnc c, and 55 Cnc f are all larger than Earth's.

55 Cnc d, discovered in 2002, has a minimum mass of 1210 Earth masses, roughly 3.82 times Jupiter's mass, and orbits every 4800 days. Among the listed planets, it has the longest year, while 55 Cnc f has the second-longest at 261 days.

55 Cnc e, a Super-Earth discovered in 2004, has a mass of 7.99 Earth masses and a radius of 1.88 Earth radii, both larger than Earth's. Its mean density is 6.68 g/cm³, 1.21 times Earth's. It completes an orbit in just 0.737 days, the shortest year among the listed planets, with 55 Cnc b holding the second-shortest at 14.7 days.