61 Ursae Majoris

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)4.54±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]

  1. ^ a b c d e f Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference aass105_1_55 was invoked but never defined (see the help page).
  3. ^ a b c d e f g h Cite error: The named reference Marfil_et_al_2020 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference apj136_793 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference yerkes53 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Nidever_et_al_2002 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference park2013 was invoked but never defined (see the help page).
  8. ^ a b c d Cite error: The named reference Chavero_et_al_2019 was invoked but never defined (see the help page).
  9. ^ a b c d Cite error: The named reference Cabot_et_al_2021 was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference apj746_1_101 was invoked but never defined (see the help page).
  11. ^ a b Cite error: The named reference aaa521_A12 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Fuhrmann2017 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Lepine2005 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference baas25_1319 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference de_Mello_et_al_2006 was invoked but never defined (see the help page).
  17. ^ Cite error: The named reference Haupt1953 was invoked but never defined (see the help page).
  18. ^ Cite error: The named reference Mittag_et_al_2017 was invoked but never defined (see the help page).
  19. ^ Cite error: The named reference Corbally_et_al_2014 was invoked but never defined (see the help page).
  20. ^ Cite error: The named reference Haakonsen_Rutledge_2009 was invoked but never defined (see the help page).
  21. ^ Cite error: The named reference Mason_et_al_2014 was invoked but never defined (see the help page).