Epsilon Ursae Minoris

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ε Ursae Minoris
Ursa Minor IAU.svg
Cercle rouge 100%.svg

Location of ε Ursae Minoris.
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ursa Minor
Right ascension 16h 45m 58.1s
Declination +82° 02' 14"
Apparent magnitude (V) +4.21
Absolute magnitude (V) −0.922[1]
Distance 303 ± 25 ly
(92.9 ± 8 pc)
Spectral type G5III
Other designations
22 Ursae Minoris, HR 6322, HD 153751, BD+82 498, FK5 912, HIP 82080, SAO 2770, GC 22749, ADS 10242, CCDM 16460+8203

Epsilon Ursae Minoris (ε UMi, ε Ursae Minoris) is a triple star system in the constellation Ursa Minor.[2] It is approximately 303 light years from Earth.[2]

The primary component, Epsilon Ursae Minoris A, is an eclipsing spectroscopic binary.[3] It is classified as a yellow G-type giant with a mean apparent magnitude of +4.21. In addition to light changes due to eclipses, the system is also classified as an RS Canum Venaticorum type variable star and its brightness varies from magnitude +4.19 to +4.23 with a period of 39.48 days, which is also the orbital period of the binary. The binary is orbited by a third component, Epsilon Ursae Minoris B, which is an 11th magnitude star,[3] 77 arcseconds away in the sky.


  1. ^ Böhm-Vitense, Erika; et al. (December 2000), "Ultraviolet Emission Lines in BA and Non-BA Giants", The Astrophysical Journal, 545 (2): 992−999, Bibcode:2000ApJ...545..992B, doi:10.1086/317850. 
  2. ^ a b "Epsilon Ursae Minoris - Variable of RS CVn type". SIMBAD Astronomical Database. Centre de Données astronomiques de Strasbourg. Retrieved 21 June 2014. 
  3. ^ a b Kaler, James B. "Epsilon Ursae Minoris". Stars. University of Illinois. Retrieved 21 June 2014.