Zeta Ursae Minoris

Zeta Ursae Minoris (ζ UMi, ζ Ursae Minoris) is a star in the constellation Ursa Minor. It 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.

ζ Ursae Minoris
Location of ζ Ursae Minoris (circled)
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]
Characteristics
Spectral type A3Vn[3]
U−B color index +0.05[2]
B−V color index +0.04[2]
Astrometry
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
Distance380 ± 20 ly
(115 ± 6 pc)
Absolute magnitude (MV)−0.98[5]
Details
Luminosity227[5] L☉
Other designations
16 Ursae Minoris, HR 5903, HD 142105, BD+78 527, FK5 590, HIP 77055, SAO 8328, GC 21243.[6]
Database references
SIMBADdata

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]

In some Arabic star charts it is listed as أخفى الفرقدين ʼakhfā al-farqadayn, meaning "the dimmer of the two calves", and paired with η Ursae Minoris as ʼanwar al-farqadayn, "the brighter of the two calves". The names may originally refer to a pair of Ibexes, and are more properly applied to γ UMi and β UMi respectively, the brighter two stars in the rectangle of Ursa Minor.[9]

References
  1. Perryman, M. A. C.; et al. (1997), "The Hipparcos Catalogue", Astronomy & Astrophysics, 323: L49–L52, Bibcode:1997A&A...323L..49P
  2. 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 (eds.). Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30. University of Toronto: International Astronomical Union. Bibcode:1967IAUS...30...57E.
  5. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
  6. "NSV 7263 – Variable Star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2009-10-28.
  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.
  9. Richard Hinckley Allen (1899). Star-names and Their Meanings. G.E. Stechert. pp. 447–460.
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