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 |
Distance | 380 ± 20 ly (115 ± 6 pc) |
Other designations | |
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]
References
- ^ 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
- ^ 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.
- ^ 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.
- ^ 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.
- ^ "NSV 7263 – Variable Star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2009-10-28.
- ^ Arabic Star Names Archived February 15, 2009, at the Wayback Machine.
- ^ "Zeta Ursae Minoris - Variable Star". SIMBAD Astronomical Database. Centre de Données astronomiques de Strasbourg. Retrieved 21 June 2014.
- ^ Kaler, James B. "Alifa al Farkadain". Stars. University of Illinois. Retrieved 21 June 2014.