55 Cancri

55 Cancri
Observation data
Constellation	Cancer
55 Cancri system
55 Cancri A
Right ascension	08h 52m 35.8113s
Declination	+28° 19' 50.957"
Apparent magnitude (V)	5.95
55 Cancri B
Right ascension	08h 52m 40.8627s
Declination	+28° 19' 58.825"
Apparent magnitude (V)	13.15
Characteristics
55 Cancri A
Spectral type	K0IV-V
U-B color index	0.63
B-V color index	0.87
55 Cancri B
Spectral type	M3.5-4V
B-V color index	1.7
Astrometry
55 Cancri A
Radial velocity	27.51 km/s
Proper motion (μ)	Right ascension: -485.872 mas/yr Declination: -233.651 mas/yr
Parallax (π)	7.4274 mas
Distance	41.06 light years (12.59 parsecs)
55 Cancri B
Proper motion (μ)	Right ascension: -481.204 mas/yr Declination: -244.779 mas/yr
Parallax (π)	80.1166
Distance	40.71 light years (12.48 parsecs)
Absolute magnitude	12.58
Orbit
Details
55 Cancri A
Mass	0.960 Solar mass
Radius	09.60 Solar radius
Luminosity	0.589 Solar luminosity
Surface gravity	4.37 cgs
Temperature	5165 K
Metallicity	-0.09 dex
Rotation	42.2 days
Age	7.4-8.7 billion years
55 Cancri B
Mass	0.255 Solar mass
Radius	0.273 Solar radius
Luminosity	0.003 Solar luminosity
Temperature	3233 K
Miscellaneous details
Other names	Copernicus (named after Nicolaus Copernicus)
Pronunciation	Ku-puh-ni-kuhs

55 Cancri is a binary star system located 40 light years away from Earth in the constellation Cancer. The system consists of two stars: A K-type main-sequence star named 55 Cancri, and a smaller red dwarf companion, 55 Cancri B.

Five extrasolar planets are known to orbit the planet: They are, in alphabetical order, 55 Cancri b, c, d, e, and f. All of them appear to orbit 55 Cancri A.