Sigma1 Ursae Majoris

For other stars with this Bayer designation, see σ Ursae Majoris.
Sigma1 Ursae Majoris
Diagram showing star positions and boundaries of the Ursa Major constellation and its surroundings
Location of σ1 Ursae Majoris (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Ursa Major
Right ascension 09h 08m 23.49946s[1]
Declination +66° 52′ 23.6492″[1]
Apparent magnitude (V) 5.14[2]
Characteristics
Spectral type K5 III[3]
U−B color index +1.80[2]
B−V color index +1.52[2]
Astrometry
Radial velocity (Rv)14.60±0.19[4] km/s
Proper motion (μ) RA: −22.68[1] mas/yr
Dec.: −40.11[1] mas/yr
Parallax (π)6.26 ± 0.30 mas[1]
Distance520 ± 20 ly
(160 ± 8 pc)
Absolute magnitude (MV)−0.93[3]
Details
Radius46[5] R☉
Luminosity560±20[3] L☉
Surface gravity (log g)1.66[6] cgs
Temperature3,940[6] K
Metallicity [Fe/H]−0.23[6] dex
Other designations
σ1 UMa, 11 Ursae Majoris, BD+67°573, HD 77800, HIP 44857, HR 3609, SAO 14769[7]
Database references
SIMBADdata

Sigma1 Ursae Majoris (σ1 UMa) is the Bayer designation for a solitary[8] star in the northern circumpolar constellation of Ursa Major. With an apparent visual magnitude of 5.14[2] it is faintly visible to the naked eye on dark nights. Based upon an annual parallax shift of 6.26 mas,[1] it is located roughly 520 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of 0.06[3] due to interstellar dust.

This is an evolved K-type giant star with a stellar classification of K5 III.[3] It is a suspected variable with an amplitude of 0.03 magnitude.[3] The measured angular diameter of the star after correcting for limb darkening is 2.67±0.04 mas,[9] which, at the estimated distance of this star, yields a physical size of about 46 times the radius of the Sun.[5] The star is radiating around 560[3] times the solar luminosity from its outer atmosphere at an effective temperature of 3,940 K.[6]

  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 c d e f g Cite error: The named reference Groenewegen2012 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference deBruijne2012 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference lang2006 was invoked but never defined (see the help page).
  6. ^ a b c d Cite error: The named reference Soubiran2010 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Richichi2005 was invoked but never defined (see the help page).