Kapteyn's Star

Kapteyn's Star

Taken from ESO Online Digitized Sky Survey
Observation data
Epoch J2000      Equinox J2000
Constellation Pictor
Right ascension 05h 11m 40.58984s[1]
Declination −45° 01′ 06.3617″[1]
Apparent magnitude (V) 8.853±0.008[2]
Characteristics
Spectral type sdM1[3] or M1.5V[2][4]
U−B color index +1.21[5]
B−V color index 1.57±0.012[2]
Variable type BY Dra[6]
Astrometry
Radial velocity (Rv)245.05±0.13[1] km/s
Proper motion (μ) RA: +6,491.223 mas/yr[1]
Dec.: −5,708.614 mas/yr[1]
Parallax (π)254.1986 ± 0.0168 mas[1]
Distance12.8308 ± 0.0008 ly
(3.9339 ± 0.0003 pc)
Absolute magnitude (MV)10.89[3]
Details[2]
Mass0.281±0.014 M☉
Radius0.291±0.025 R☉
Luminosity0.012 L☉
Surface gravity (log g)4.96±0.13 cgs
Temperature3,570±80 K
Metallicity [Fe/H]−0.86±0.05 dex
Rotation124.71±0.19 d[7]
Rotational velocity (v sin i)9.15[8] km/s
Age11.5+0.5
−1.5 Gyr
Other designations
VZ Pictoris, CD−45°1841, CP(D)-44°612, GJ 191, HD 33793, HIP 24186, SAO 217223, LFT 395, LHS 29, LTT 2200[5]
Database references
SIMBADThe star
planet b
planet c

Kapteyn's Star is a class M1 red subdwarf about 12.83 light-years from Earth in the southern constellation Pictor; it is the closest halo star to the Solar System. With an apparent magnitude of nearly 9, it is visible through binoculars or a telescope.[9]

Its diameter is 30% of the Sun's, but its luminosity just 1.2% that of the Sun. It may have once been part of the globular cluster Omega Centauri, itself the likely core of a dwarf galaxy swallowed up by the Milky Way in the distant past. The discovery of two planets—Kapteyn b and Kapteyn c—was announced in 2014,[10] but had a mixed history of rejections and confirmations, until a 2021 study refuted both planets. The "planets" are in fact artifacts of the star's rotation and activity.[7]

  1. ^ a b c d e Cite error: The named reference GaiaDR3 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Guinan2016 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference mnras403_4_1949 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference aaa505_1_205 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference var was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference BortleFausey2021 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference mnras407_3_1657 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference scinews was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference planets was invoked but never defined (see the help page).