Kapteyn's Star
Star
Kapteyn's Star - a nearby red subdwarf 12.8 light-years away in Pictor, and one of the strangest stars in the neighbourhood: an ancient, metal-poor HALO star racing backwards through the Galaxy, probably torn from the disrupted globular cluster now seen as Omega Centauri. No planets are confirmed.
Open in 3D viewSee Kapteyn's Star in the live, interactive 3D map
Key facts
Mass
5.59 × 10²⁹ kg
0.281 M☉
Radius
202,449 km
29% of the Sun's radius
Surface temperature
3,570 K (3297 °C)
Luminosity
4.59 × 10²⁴ W
Spectral type
sdM1 (metal-poor red subdwarf)
Science
Physical
- Mass
- 5.59 × 10²⁹ kg · 0.281 M☉
- Radius
- 202,449 km · 29% of the Sun's radius
- Density
- 16,080 kg/m³ · 16× water
- Spectral type
- sdM1 (metal-poor red subdwarf)
Composition
- By mass
- A red subdwarf about 28% of the Sun's mass. Very metal-poor and extremely old (~11 billion years), it belongs to the Galaxy's halo and moves retrograde — likely stripped from the progenitor of Omega Centauri.
Temperature
- Surface
- 3,570 K (3297 °C)
Radiation & temperature
- Luminosity
- 4.59 × 10²⁴ W · 0.012 L☉
- Surface temperature
- 3,570 K (3297 °C)
- Peak wavelength
- 812 nm · near-infrared (mostly invisible to the eye)
Discovery & history
- Discovered
- January 1, 1898
- By
- Jacobus C. Kapteyn
- Name
- Named for the Dutch astronomer Jacobus Cornelius Kapteyn, who measured its record proper motion in 1898.
In 1898 Jacobus Kapteyn found this star's enormous proper motion - then the largest known - marking it as a very close, fast neighbour. Two planet claims in 2014 caused excitement but were shown by 2021 to be artefacts of the star's rotation, and are not shown here.
Images
Images from open archives · credit shown per image