Astronomy:61 Ursae Majoris

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Short description: Star in the Ursa Major constellation
61 Ursae Majoris
Location of 61 Ursae Majoris (circled in red)
Observation data
Equinox J2000.0]] (ICRS)
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[1] mas
Distance31.24 ± 0.04 ly
(9.58 ± 0.01 pc)
Absolute magnitude (MV)5.53±0.006[7]
Details
Mass0.94±0.06[8] M☉
Radius0.845±0.015[8] R☉
Luminosity0.588±0.007[8] L☉
Surface gravity (log g)4.52±0.08[8] cgs
Temperature5,488±44[3] K
Metallicity [Fe/H]−0.03±0.03[3] dex
Rotation17.1 days[9]
Rotational velocity (v sin i)3.3[3] km/s
Age1.4±0.2[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[10]
Database references
SIMBADdata

61 Ursae Majoris, abbreviated 61 UMa, is a single[11] 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.[12]

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.[13] It is considered a solar-type star, having physical properties that make it similar to the Sun.[14] The star has 93%[15] of the mass of the Sun and 86%[16] of the Sun's radius. It is roughly two[15] billion years old and is spinning with a projected rotational velocity of 3.3 km/s,[3] for a period of 17.1 days.[9] 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%[17] 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.[18] 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.[19] It has an active chromosphere that exhibits strong and persistent starspot activity.[16] A flare event was captured in 2013 while the star was being observed by the VATT,[20] and the star has been detected as a source of X-ray emission.[21]

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.[16] 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°.[22]

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.[23]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  2. ↑ 2.0 2.1 Cornide, M.; Rego, M. (October 1984). "Iron abundances in G dwarfs". Astrophysics and Space Science 105 (1): 55–65. doi:10.1007/BF00651207. Bibcode: 1984Ap&SS.105...55C. 
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 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. doi:10.1093/mnras/staa058. Bibcode: 2020MNRAS.492.5470M. 
  4. ↑ 4.0 4.1 Wilson, O. C. (November 1962). "Relationship Between Colors and Spectra of Late Main-Sequence Stars". Astrophysical Journal 136: 793. doi:10.1086/147437. Bibcode: 1962ApJ...136..793W. 
  5. ↑ 5.0 5.1 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. doi:10.1086/145697. Bibcode: 1953ApJ...117..313J. 
  6. ↑ 6.0 6.1 Nidever, David L. et al. (August 2002). "Radial Velocities for 889 Late-Type Stars". The Astrophysical Journal Supplement Series 141 (2): 503–522. doi:10.1086/340570. Bibcode: 2002ApJS..141..503N. 
  7. ↑ Park, Sunkyung et al. (2013). "Wilson-Bappu Effect: Extended to Surface Gravity". The Astronomical Journal 146 (4): 73. doi:10.1088/0004-6256/146/4/73. Bibcode: 2013AJ....146...73P. 
  8. ↑ 8.0 8.1 8.2 8.3 8.4 Metcalfe, Travis S.; Strassmeier, Klaus G.; Ilyin, Ilya V.; Saders, Jennifer L. van; Ayres, Thomas R.; Finley, Adam J.; Kochukhov, Oleg; Petit, Pascal et al. (2023-04-19). "Constraints on Magnetic Braking from the G8 Dwarf Stars 61 UMa and τ Cet". The Astrophysical Journal Letters. 
  9. ↑ 9.0 9.1 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. doi:10.1051/0004-6361/201014948. Bibcode: 2010A&A...521A..12M. 
  10. ↑ "61 UMa". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=61+UMa. 
  11. ↑ Fuhrmann, K. et al. (February 2017). "Multiplicity among Solar-type Stars". The Astrophysical Journal 836 (1): 23. doi:10.3847/1538-4357/836/1/139. 139. Bibcode: 2017ApJ...836..139F. 
  12. ↑ 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. doi:10.1086/427854. Bibcode: 2005AJ....129.1483L. 
  13. ↑ 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. http://www.astro.utoronto.ca/~garrison/mkstds.html. Retrieved 2012-02-04. 
  14. ↑ de Mello, G. F. Porto et al. (2006). "Astrobiologically interesting stars within 10 parsecs of the Sun". Astrobiology 6 (2): 308–331. doi:10.1089/ast.2006.6.308. PMID 16689649. Bibcode: 2006AsBio...6..308P. 
  15. ↑ 15.0 15.1 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. doi:10.1093/mnras/stz1496. Bibcode: 2019MNRAS.487.3162C. 
  16. ↑ 16.0 16.1 16.2 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. doi:10.3847/1538-3881/abc41e. 26. Bibcode: 2021AJ....161...26C. 
  17. ↑ 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. doi:10.1088/0004-637X/746/1/101. Bibcode: 2012ApJ...746..101B.  See Table 10.
  18. ↑ Haupt, Hermann (August 1953). "Radial Velocity Observations of 61 Ursae Majoris". Publications of the Astronomical Society of the Pacific 65 (385): 219. doi:10.1086/126602. Bibcode: 1953PASP...65..219H. 
  19. ↑ 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. doi:10.1051/0004-6361/201630262. A87. Bibcode: 2017A&A...607A..87M. 
  20. ↑ Corbally, Christopher J.; Gray, Richard O.; Saken, Jon M.; Lambert, Ryan A. (January 2015). "Short-term Activity in Young Solar Analogs". in van Belle, G.; Harris, H. C.. 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. 
  21. ↑ 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. doi:10.1088/0067-0049/184/1/138. Bibcode: 2009ApJS..184..138H. 
  22. ↑ Mason, B. D. et al. (2014). "The Washington Visual Double Star Catalog". The Astronomical Journal 122 (6): 3466–3471. doi:10.1086/323920. Bibcode: 2001AJ....122.3466M. 
  23. ↑ Niven, Larry (1970). Ringworld. Ballantine Books. chapters 2 and 6. ISBN 0-345-02046-4. 



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