61 Ursae Majoris
Observation data
Epoch J2000      Equinox J2000
Constellation Ursa Major
Right ascension 11h 41m 03.01594s[1]
Declination +34° 12′ 05.8824″[1]
Apparent magnitude (V) 5.35[2]
Characteristics
Evolutionary stage Main sequence[3]
Spectral type G8V[4]
U−B color index +0.27[5]
B−V color index +0.69[5]
Variable type Suspected
Astrometry
Radial velocity (Rv)−5.18±0.08[6] km/s
Proper motion (μ) RA: −12.247[1] mas/yr
Dec.: −381.257[1] mas/yr
Parallax (π)104.3904 ± 0.1287 mas[1]
Distance31.24 ± 0.04 ly
(9.58 ± 0.01 pc)
Absolute magnitude (MV)5.53±0.006[7]
Details
Mass0.93±0.02[8] M☉
Radius0.86±0.02[9] R☉
Luminosity0.609±0.009[10] L☉
Surface gravity (log g)4.43±0.06[3] cgs
Temperature5,488±44[3] K
Metallicity [Fe/H]−0.03±0.03[3] dex
Rotation17.1 days[11]
Rotational velocity (v sin i)3.3[3] km/s
Age2.1±1.7[8] Gyr
Other designations
61 UMa, NSV 5291, BD+35°2270, FK5 1300, GJ 434, HD 101501, HIP 56997, HR 4496, SAO 62655, WDS J11411+3412A, LTT 13200[12]
Database references
SIMBADdata

61 Ursae Majoris, abbreviated 61 UMa, is a single[13] star in the northern circumpolar constellation of Ursa Major. It has a yellow-orange hue and is dimly visible to the naked eye with an apparent visual magnitude of 5.35.[2] The distance to this star is 31.2 light years based on parallax,[1] and it is drifting closer with a radial velocity of −5.2 km/s.[6] The star has a relatively high proper motion traversing the sky at the rate of 0.381″ yr−1.[14]

The stellar classification of 61 UMa is G8V,[4] matching a late G-type main-sequence star. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.[15] It is considered a solar-type star, having physical properties that make it similar to the Sun.[16] The star has 93%[8] of the mass of the Sun and 86%[9] of the Sun's radius. It is roughly two[8] billion years old and is spinning with a projected rotational velocity of 3.3 km/s,[3] for a period of 17.1 days.[11] The metallicity, or abundance of elements with higher atomic number than helium, appears about the same as in the Sun.[3] The star is radiating 61%[10] of the luminosity of the Sun from its photosphere at an effective temperature of 5,488K.[3]

During the 1950s, Karl Pilowski reported that photographic plates taken of the star appeared to show a variability of 0.2 in magnitude. Follow-up studies initially failed to confirm this variability, and it was found not to be an eclipsing binary based on radial velocity measurements.[17] The star's photosphere is rotating differentially, and the rotation period, typically in the range of 16-18 days, shows a larger difference between different latitudes than for most other stars.[18] It has an active chromosphere that exhibits strong and persistent starspot activity.[9] A flare event was captured in 2013 while the star was being observed by the VATT,[19] and the star has been detected as a source of X-ray emission.[20]

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. A radial velocity survey completed in 2020 has indicated that giant planetary companions are absent.[9] A magnitude 11.35 stellar visual companion was reported by O. Struve in 1850. As of 2015, this star was located at an angular separation of 158.90″ from the brighter star, along a position angle of 86°.[21]

In the science fiction of Larry Niven's Known Space universe, the homeworld of the major race the Kzinti is the third planet in orbit around 61 Ursae Majoris.[22]

References

  1. 1 2 3 4 5 6 Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. 1 2 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. S2CID 120792029.
  3. 1 2 3 4 5 6 7 8 Marfil, E.; et al. (March 2020). "Stellar atmospheric parameters of FGK-type stars from high-resolution optical and near-infrared CARMENES spectra". Monthly Notices of the Royal Astronomical Society. 492 (4): 5470–5507. arXiv:2001.01495. Bibcode:2020MNRAS.492.5470M. doi:10.1093/mnras/staa058.
  4. 1 2 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.
  5. 1 2 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.
  6. 1 2 Nidever, David L.; et al. (August 2002). "Radial Velocities for 889 Late-Type Stars". The Astrophysical Journal Supplement Series. 141 (2): 503–522. arXiv:astro-ph/0112477. Bibcode:2002ApJS..141..503N. doi:10.1086/340570. S2CID 51814894.
  7. ↑ Park, Sunkyung; et al. (2013). "Wilson-Bappu Effect: Extended to Surface Gravity". The Astronomical Journal. 146 (4): 73. arXiv:1307.0592. Bibcode:2013AJ....146...73P. doi:10.1088/0004-6256/146/4/73. S2CID 119187733.
  8. 1 2 3 4 Chavero, C.; et al. (August 2019). "Emerging trends in metallicity and lithium properties of debris disc stars". Monthly Notices of the Royal Astronomical Society. 487 (3): 3162–3177. arXiv:1905.12066. Bibcode:2019MNRAS.487.3162C. doi:10.1093/mnras/stz1496.
  9. 1 2 3 4 Cabot, Samuel H. C.; et al. (January 2021). "EXPRES. II. Searching for Planets around Active Stars: A Case Study of HD 101501". The Astronomical Journal. 161 (1): 20. arXiv:2010.14717. Bibcode:2021AJ....161...26C. doi:10.3847/1538-3881/abc41e. S2CID 225094601. 26.
  10. 1 2 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:1112.3316. Bibcode:2012ApJ...746..101B. doi:10.1088/0004-637X/746/1/101. S2CID 18993744. See Table 10.
  11. 1 2 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:1007.1132. Bibcode:2010A&A...521A..12M. doi:10.1051/0004-6361/201014948. S2CID 119209183.
  12. ↑ "61 UMa". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-12-31.
  13. ↑ Fuhrmann, K.; et al. (February 2017). "Multiplicity among Solar-type Stars". The Astrophysical Journal. 836 (1): 23. Bibcode:2017ApJ...836..139F. doi:10.3847/1538-4357/836/1/139. 139.
  14. ↑ Lépine, Sébastien; Shara, Michael M. (March 2005). "A Catalog of Northern Stars with Annual Proper Motions Larger than 0.15" (LSPM-NORTH Catalog)". The Astronomical Journal. 129 (3): 1483–1522. arXiv:astro-ph/0412070. Bibcode:2005AJ....129.1483L. doi:10.1086/427854. S2CID 2603568.
  15. ↑ 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. Archived from the original on 2019-06-25. Retrieved 2012-02-04.
  16. ↑ de Mello, G. F. Porto; et al. (2006). "Astrobiologically interesting stars within 10 parsecs of the Sun". Astrobiology. 6 (2): 308–331. arXiv:astro-ph/0511180. Bibcode:2006AsBio...6..308P. doi:10.1089/ast.2006.6.308. PMID 16689649. S2CID 119459291.
  17. ↑ Haupt, Hermann (August 1953). "Radial Velocity Observations of 61 Ursae Majoris". Publications of the Astronomical Society of the Pacific. 65 (385): 219. Bibcode:1953PASP...65..219H. doi:10.1086/126602.
  18. ↑ Mittag, M.; et al. (November 2017). "Stellar rotation periods determined from simultaneously measured Ca II H&K and Ca II IRT lines". Astronomy & Astrophysics. 607: 39. Bibcode:2017A&A...607A..87M. doi:10.1051/0004-6361/201630262. A87.
  19. ↑ Corbally, Christopher J.; et al. (January 2015). van Belle, G.; Harris, H. C. (eds.). Short-term Activity in Young Solar Analogs. 18th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, Proceedings of the conference held at Lowell Observatory, 8-14 June, 2014. pp. 307–312. Bibcode:2015csss...18..307C.
  20. ↑ Haakonsen, Christian Bernt; Rutledge, Robert E. (September 2009). "XID II: Statistical Cross-Association of ROSAT Bright Source Catalog X-ray Sources with 2MASS Point Source Catalog Near-Infrared Sources". The Astrophysical Journal Supplement. 184 (1): 138–151. arXiv:0910.3229. Bibcode:2009ApJS..184..138H. doi:10.1088/0067-0049/184/1/138. S2CID 119267456.
  21. ↑ Mason, B. D.; et al. (2014). "The Washington Visual Double Star Catalog". The Astronomical Journal. 122 (6): 3466–3471. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.
  22. ↑ Niven, Larry (1970). Ringworld. Ballantine Books. chapters 2 and 6. ISBN 0-345-02046-4.
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