Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Cancer |
Right ascension | 08h 23m 55.20829s [1] |
Declination | +10° 37′ 55.4169″ [1] |
Apparent magnitude (V) | 6.08 [2] |
Characteristics | |
Spectral type | M2III [3] |
B−V color index | 1.507±0.004 [4] |
Variable type | suspected [5] |
Astrometry | |
Radial velocity (Rv) | 4.53 [1] km/s |
Proper motion (μ) |
RA: −0.843
[1]
mas/
yr Dec.: −22.943 [1] mas/ yr |
Parallax (π) | 4.1258 ± 0.0272 mas [1] |
Distance | 791 ± 5
ly (242 ± 2 pc) |
Details | |
Radius | 53 [6] R☉ |
Luminosity | 587 [6] L☉ |
Temperature | 3,885 [6] K |
Other designations | |
Database references | |
SIMBAD | data |
21 Cancri is a double star in the northern zodiac constellation of Cancer. It is just visible to the naked eye as a dim, red-hued star with an apparent visual magnitude of 6.08. [2] The star is located around 791 light years away from the Sun, based on parallax. It is moving further from the Earth with a heliocentric radial velocity of 35 km/s. [6]
The brighter component is an aging red giant with a stellar classification of M2III. [3] It is currently on the asymptotic giant branch, indicating this is a highly evolved star that has exhausted both its core hydrogen and core helium. [7] This is a suspected variable star. [5] It has expanded to 53 [6] times the radius of the Sun and is radiating 587 [6] times the Sun's luminosity from its swollen photosphere at an effective temperature of 3,885 K. [6] A 9th magnitude companion star is located one arc second away. [7]