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Kapteyn's Star

Kapteyn's Star
Kapteyn's Star is located in 100x100
Kapteyn's Star
Kapteyn's Star

Location of Kapteyn's Star in the constellation Pictor
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).

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