Omega Ursae Majoris

ω Ursae Majoris
Location of ω Ursae Majoris (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Ursa Major
Right ascension 10h 53m 58.74035s[1]
Declination +43° 11′ 23.8483″[1]
Apparent magnitude (V) 4.61[2]
Characteristics
Spectral type A1VsSi:[3] or A0 IV−V[4]
U−B color index −0.11[2]
B−V color index −0.04[2]
Astrometry
Radial velocity (Rv)−18.70±0.80[5] km/s
Proper motion (μ) RA: +42.97[1] mas/yr
Dec.: −23.62[1] mas/yr
Parallax (π)13.24 ± 0.50 mas[1]
Distance246 ± 9 ly
(76 ± 3 pc)
Absolute magnitude (MV)+0.86[6]
Orbit[7]
Period (P)15.8307 d
Eccentricity (e)0.31
Periastron epoch (T)2435185.246 JD
Argument of periastron (ω)
(secondary)		27.3°
Semi-amplitude (K1)
(primary)		22.2 km/s
Details
Radius2.5[8] R☉
Luminosity76[9] L☉
Surface gravity (log g)3.88[4] cgs
Temperature9,647[9] K
Rotational velocity (v sin i)47[10] km/s
Age325[6] Myr
Other designations
ω UMa, 45 Ursae Majoris, BD+43°2058, FK5 2870, HD 94334, HIP 53295, HR 4248, SAO 43512[11]
Database references
SIMBADdata

Omega Ursae Majoris (Omega UMa, ω Ursae Majoris, ω UMa) is a binary star system in the northern circumpolar constellation of Ursa Major. It is visible to the naked eye with an apparent visual magnitude of 4.61.[2] Based upon an annual parallax shift of 13.24 mas,[1] it is roughly 246 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of 0.11 due to interstellar dust.[6]

This is a single-lined spectroscopic binary star system with an orbital period of 15.8 days and an eccentricity of 0.31.[7] The primary member, component A, is an A-type main sequence star with a stellar classification of A1VsSi:.[3] The stellar spectrum has the appearance of a hot Am star, showing overabundances of many iron-peak and heavier elements, but an underabundance of helium.[12] In particular, it has an abnormal abundance of silicon.[13]

  1. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Mermilliod1986 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Cowley1969 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference adelman2004 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference deBruijne2012 was invoked but never defined (see the help page).
  6. ^ a b c Cite error: The named reference Gontcharov2012 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Pourbaix2004 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference cadars2 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference Mcdonald2012 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Royer2007 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Caliskan1997 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Renson2009 was invoked but never defined (see the help page).