Kruger 60

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Kruger 60 A/B
Observation data
Epoch J2000      Equinox
Constellation Cepheus
Kruger 60 A
Right ascension 22h 27m 59.4677s[1]
Declination +57° 41′ 45.150″[1]
Apparent magnitude (V) 9.59
Kruger 60 B
Right ascension 22h 27m 59.568s[1]
Declination +57° 41′ 45.28″[1]
Apparent magnitude (V) 11.40
Spectral type M3V/M4V[2]
U−B color index 1.27/1.3
B−V color index 1.65/1.8
Variable type None/Flare star
Radial velocity (Rv) –33.1/–31.9 km/s
Proper motion (μ) RA: –870.23 mas/yr
Dec.: –471.10 mas/yr
Parallax (π) 247.5 ± 1.5[3] mas
Distance 13.18 ± 0.08 ly
(4.04 ± 0.02 pc)
Absolute magnitude (MV) 11.76/13.46
Mass 0.271/0.176[4] M
Radius 0.35/0.24[5] R
Luminosity 0.010/0.0034 L
Temperature 3180/2890 K K
Metallicity –0.04[6]
Primary Kruger 60 A
Companion Kruger 60 B
Period (P) 44.67 yr
Semi-major axis (a) 2.383″
Eccentricity (e) 0.410
Inclination (i) 167.2°
Longitude of the node (Ω) 154.5°
Periastron epoch (T) 1970.22
Argument of periastron (ω)
Other designations
DO Cephei, G 232-075, GJ 860 A/B, BD +56°2783, HD 239960, LHS 3814/3815, GCTP 5438.00, ADS 15972, Vys 207 A/B, HIP 110893.[8]
Database references
SIMBAD The system

Kruger 60 (DO Cephei) is a binary star system located 13.15 light-years from the Sun. These red dwarf stars orbit each other every 44.6 years.

The larger, primary star is designated component A, while the secondary, smaller star is labeled component B. Component A has about 27% of the Sun's mass and 35% of the Sun's radius. Component B has about 18% of the Sun's mass and 24% of the Sun's radius.[4][5] Component B is a flare star and has been given the variable star designation "DO Cephei".[9] It is an irregular flare that typically doubles in brightness and then returns to normal over an 8-minute period.[citation needed]

On average, the two stars are separated by 9.5 AUs, which is roughly the average distance of Saturn from the Sun. However, their eccentric mutual orbit causes their distance to vary between 5.5 AUs at periastron, to 13.5 at apastron.[citation needed]

This system is orbiting through the Milky Way at a distance from the core that varies from 7–9 kpc with an orbital eccentricity of 0.126–0.130.[10] The closest approach to the Sun will occur in about 88,600 years when this system will come within 1.95 parsecs.[11]

In fiction[edit]

In the novel Waiting for Omega (2016) by David Villa, the protagonist's second home (after Earth) is given as a tidally locked planet orbiting Kruger60-A, where he lives for some hundreds of years, first below the ground and then, on completion of terraforming operations, above it. [12]

The system in also mentioned in passing in Vernor Vinge's A Fire Upon the Deep[citation needed].


  1. ^ a b c d Perryman, M. A. C.; Lindegren; Kovalevsky; Hoeg; Bastian; Bernacca; Crézé; Donati; Grenon; et al. (1997). "The Hipparcos Catalogue". Astronomy and Astrophysics. 323: L49–L52. Bibcode:1997A&A...323L..49P. 
  2. ^ Henry, Todd J.; et al. (October 1994). "The solar neighborhood, 1: Standard spectral types (K5-M8) for northern dwarfs within eight parsecs". The Astronomical Journal. 108 (4): 1437–1444. Bibcode:1994AJ....108.1437H. doi:10.1086/117167. 
  3. ^ Söderhjelm, Staffan (1999). "HIP 110893". Visual binary orbits and masses post Hipparcos. Retrieved 2014-10-21. 
  4. ^ a b Delfosse, X.; Forveille; Ségransan; Beuzit; Udry; Perrier; Mayor (December 2000). "Accurate masses of very low mass stars. IV. Improved mass-luminosity relations". Astronomy and Astrophysics. 364: 217–224. Bibcode:2000A&A...364..217D. arXiv:astro-ph/0010586Freely accessible. 
  5. ^ a b Pasinetti Fracassini, L. E.; et al. (February 2001). "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics". Astronomy and Astrophysics. 367 (2): 521–524. Bibcode:2001A&A...367..521P. arXiv:astro-ph/0012289Freely accessible. doi:10.1051/0004-6361:20000451.  The data is from the Vizier II/224 catalogue.
  6. ^ Bonfils, X.; et al. (November 2005). "Metallicity of M dwarfs. I. A photometric calibration and the impact on the mass-luminosity relation at the bottom of the main sequence". Astronomy and Astrophysics. 442 (2): 635–642. Bibcode:2005A&A...442..635B. arXiv:astro-ph/0503260Freely accessible. doi:10.1051/0004-6361:20053046.  Only listed for component A.
  7. ^ Heintz, W. D. (August 1986). "Orbits of 20 visual binaries". Astronomy and Astrophysics Supplement Series. 65 (2): 411–417. Bibcode:1986A&AS...65..411H. 
  8. ^ "NSV 14168 – Variable Star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2009-09-28. 
  9. ^ White, Stephen M.; et al. (December 1989). "A VLA survey of nearby flare stars". Astrophysical Journal Supplement Series. 71: 895–904. Bibcode:1989ApJS...71..895W. doi:10.1086/191401. 
  10. ^ Allen, C.; Herrera, M. A. (1998). "The galactic orbits of nearby UV Ceti stars". Revista Mexicana de Astronomia y Astrofisica. 34: 37–46. Bibcode:1998larm.confE.115A. 
  11. ^ García-Sánchez, J.; et al. (November 2001). "Stellar encounters with the solar system". Astronomy and Astrophysics. 379 (2): 634–659. Bibcode:2001A&A...379..634G. doi:10.1051/0004-6361:20011330. 
  12. ^ Villa, David (2016). Waiting for Omega. Smashwords. ISBN 9781370669363. 


Further reading[edit]