Zeta Ursae Minoris

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

Location of ζ Ursae Minoris.
Observation data
Epoch J2000      Equinox J2000
Constellation Ursa Minor
Right ascension 15h 44m 03.5193s[1]
Declination +77° 47′ 40.175″[1]
Apparent magnitude (V) +4.32[2]
Spectral type A3Vn[3]
U−B color index +0.05[2]
B−V color index +0.04[2]
Radial velocity (Rv) –13.1[4] km/s
Proper motion (μ) RA: 20.07[1] mas/yr
Dec.: –2.50[1] mas/yr
Parallax (π) 8.68 ± 0.47[1] mas
Distance 380 ± 20 ly
(115 ± 6 pc)
Other designations
16 Ursae Minoris, HR 5903, HD 142105, BD+78 527, FK5 590, HIP 77055, SAO 8328, GC 21243.[5]
Database references

Zeta Ursae Minoris (ζ UMi, ζ Ursae Minoris) is a star in the constellation Ursa Minor. It has the traditional name Akhfa al Farkadain,[6] from the Arabic أخفى الفرقدين aḫfa al-farqadayn "the dimmer of the two calves", as opposed to Anwar al Farkadain (η UMi) "the brighter of the two calves"[citation needed]. These names were originally applied to Pherkad and Kochab, respectively, the other two stars in the rectangle of Ursa Minor.

Zeta Ursae Minoris is a white stellar class A-type main sequence star with an apparent magnitude of +4.28.[7] It is approximately 380 light years from Earth.

Despite its classification as a main sequence dwarf star, Zeta UMi is 3.4 times the mass of the sun and its luminosity is about 200 solar luminosities. At a surface temperature of 8,700 kelvins, this star is actually on the verge of becoming a giant star. Zeta UMi may also be a variable of the Delta Scuti type.[8]


  1. ^ a b c d e Perryman, M. A. C.; et al. (1997), "The Hipparcos Catalogue", Astronomy & Astrophysics, 323: L49–L52, Bibcode:1997A&A...323L..49P 
  2. ^ a b c Johnson, H. L.; et al. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory. 4 (99). Bibcode:1966CoLPL...4...99J. 
  3. ^ Cowley, A.; Cowley, C.; Jaschek, M.; Jaschek, C. (April 1969). "A study of the bright A stars. I. A catalogue of spectral classifications". Astronomical Journal. 74: 375–406. Bibcode:1969AJ.....74..375C. doi:10.1086/110819. 
  4. ^ Evans, D. S. (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities". In Batten, Alan Henry; Heard, John Frederick. Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30. University of Toronto: International Astronomical Union. Bibcode:1967IAUS...30...57E. Retrieved 2009-09-10. 
  5. ^ "NSV 7263 – Variable Star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2009-10-28. 
  6. ^ Arabic Star Names Archived February 15, 2009, at the Wayback Machine.
  7. ^ "Zeta Ursae Minoris - Variable Star". SIMBAD Astronomical Database. Centre de Données astronomiques de Strasbourg. Retrieved 21 June 2014. 
  8. ^ Kaler, James B. "Alifa al Farkadain". Stars. University of Illinois. Retrieved 21 June 2014.