61 Ursae Majoris

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61 Ursae Majoris
Observation data
Epoch J2000      Equinox J2000
Constellation Ursa Major
Right ascension 11h 41m 03.0153s[1]
Declination +34° 12′ 05.888″[1]
Apparent magnitude (V) 5.35[2]
Spectral type G8V[3]
U−B color index +0.27[4]
B−V color index +0.69[4]
R−I color index 0.37[citation needed]
Variable type Suspected
Radial velocity (Rv) −5.4[5] km/s
Proper motion (μ) RA: −13.95[1] mas/yr
Dec.: −380.46[1] mas/yr
Parallax (π) 104.81 ± 0.72[1] mas
Distance 31.1 ± 0.2 ly
(9.54 ± 0.07 pc)
Absolute magnitude (MV) 5.41
Mass 0.85[6] M
Radius 0.940 ± 0.010[7] R
Luminosity 0.609 ± 0.009[7] L
Surface gravity (log g) 4.69[2] cgs
Temperature 5,270 ± 32[7] K
Metallicity [Fe/H] +0.03[2] dex
Rotation 17.1 days[8]
Rotational velocity (v sin i) 8[9] km/s
Age 0.8–1.2[10] Gyr
Other designations
BD +35°2270, FK5 1300, GCTP 2699.00, GJ 434, HD 101501, HIP 56997, HR 4496, LTT 13200, SAO 62655, NSV 5291.
Database references

61 Ursae Majoris (61 UMa) is an orange-yellow G8 main-sequence star in the constellation Ursa Major. It is somewhat smaller and fainter than the Sun, and can just barely be seen by the unaided eye (based on a magnitude limit of 6). Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.[11]

No substellar companions have been observed in orbit around this star, and it appears to lack a dust ring as is found around some comparable stars. It lies near the same line of sight as the sub-giant star HD 101212, although it is unclear whether these two stars are gravitationally bound or even in physical proximity.

The space velocity components of this star are [U, V, W] = [+8, −16, −4] km/s. It is orbiting the galaxy at a mean distance of 7.9 kpc (26×10^3 ly) from the core with an eccentricity of 0.06.[12]

See also[edit]


  1. ^ a b c d e Perryman, M. A. C.; et al. (April 1997). "The HIPPARCOS Catalogue". Astronomy & Astrophysics. 323: L49–L52. Bibcode:1997A&A...323L..49P. 
  2. ^ a b c Cornide, M.; Rego, M. (October 1984). "Iron abundances in G dwarfs". Astrophysics and Space Science. 105 (1): 55–65. Bibcode:1984Ap&SS.105...55C. doi:10.1007/BF00651207. 
  3. ^ Wilson, O. C. (November 1962). "Relationship Between Colors and Spectra of Late Main-Sequence Stars". Astrophysical Journal. 136: 793. Bibcode:1962ApJ...136..793W. doi:10.1086/147437. 
  4. ^ a b Johnson, H. L.; Morgan, W. W. (1953). "Fundamental stellar photometry for standards of spectral type on the revised system of the Yerkes spectral atlas". Astrophysical Journal. 117: 313–352. Bibcode:1953ApJ...117..313J. doi:10.1086/145697. 
  5. ^ Wilson, Ralph Elmer (1953). General Catalogue of Stellar Radial Velocities. Washington: Carnegie Institution of Washington. Bibcode:1953GCRV..C......0W. 
  6. ^ Takeda, G.; et al. (2007). "Stellar parameters of nearby cool stars. II. Physical properties of ~1000 cool stars from the SPOCS catalog". Astrophysical Journal Supplement Series. 168: 297–318. Bibcode:2008yCat..21680297T. doi:10.1086/509763.  Note: see VizieR catalogue J/ApJS/168/297.
  7. ^ a b c Boyajian, Tabetha S.; et al. (February 2012), "Stellar Diameters and Temperatures. I. Main-sequence A, F, and G Stars", The Astrophysical Journal, 746 (1): 101, arXiv:1112.3316free to read, Bibcode:2012ApJ...746..101B, doi:10.1088/0004-637X/746/1/101 . See Table 10.
  8. ^ Maldonado, J.; et al. (October 2010), "A spectroscopy study of nearby late-type stars, possible members of stellar kinematic groups", Astronomy and Astrophysics, 521: A12, arXiv:1007.1132free to read, Bibcode:2010A&A...521A..12M, doi:10.1051/0004-6361/201014948 
  9. ^ Bernacca, P. L.; Perinotto, M. (1970). "A catalogue of stellar rotational velocities". Contributi Osservatorio Astronomico di Padova in Asiago. 239 (1). Bibcode:1970CoAsi.239....1B. 
  10. ^ Mamajek, Eric E.; Hillenbrand, Lynne A. (November 2008). "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics". The Astrophysical Journal. 687 (2): 1264–1293. arXiv:0807.1686free to read. Bibcode:2008ApJ...687.1264M. doi:10.1086/591785. 
  11. ^ Garrison, R. F. (December 1993), "Anchor Points for the MK System of Spectral Classification", Bulletin of the American Astronomical Society, 25: 1319, Bibcode:1993AAS...183.1710G, retrieved 2012-02-04 
  12. ^ de Mello, G. F. Porto; del Peloso, E. F.; Ghezzi, L. (2006). "Astrobiologically interesting stars within 10 parsecs of the Sun". Astrobiology. 6 (2): 308–331. arXiv:astro-ph/0511180free to read. Bibcode:2006AsBio...6..308P. doi:10.1089/ast.2006.6.308. PMID 16689649. Retrieved 2008-01-17. 

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