Kapteyn's Star was originally cataloged by the Dutch astronomer, Jacobus Kapteyn, in 1898.[10] While he was reviewing star charts and photographic plates he noted the star's very high proper motion of more than 8 arc seconds per year. Later, the star became referred to as Kapteyn's Star, in honor of its discoverer.[11] At that time, it had the highest proper motion of any star known, dethroning Groombridge 1830. With the discovery of Barnard's Star in 1916,[12] Kapteyn's Star dropped to second place, where it remains.[6][11] On 2014, two super-Earth planet candidates in orbit around the star were announced.[13]
Observation data Epoch J2000 Equinox J2000 |
|
---|---|
Constellation | Pictor |
Right ascension | 05h 11m 40.58112s[1] |
Declination | −45° 01′ 06.2899″[1] |
Apparent magnitude (V) | 8.853[2] |
Characteristics | |
Spectral type | sdM1[2] |
U−B color index | +1.21[3] |
B−V color index | +1.57[3] |
Variable type | BY Dra[4] |
Astrometry | |
Radial velocity (Rv) | +245.2[5] km/s |
Proper motion (μ) | RA: +6,505.08[1] mas/yr Dec.: -5,730.84[1] mas/yr |
Parallax (π) | 255.66 ± 0.91[1] mas |
Distance | 12.76 ± 0.05 ly (3.91 ± 0.01 pc) |
Details | |
Mass | 0.274[6] M☉ |
Radius | 0.291 ± 0.025[7] R☉ |
Surface gravity (log g) | 4.96[6] cgs |
Temperature | 3,570[6] K |
Metallicity [Fe/H] | –0.99 ± 0.04[8] dex |
Rotational velocity(v sin i) | 9.15[9] km/s |
Age | ~10[6] Gyr |
Other designations | |