Delta Ursae Minoris
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Ursa Minor[1] |
Right ascension | 17h 32m 12.99671s[2] |
Declination | 86° 35′ 11.2584″[2] |
Apparent magnitude (V) | 4.36[3] |
Characteristics | |
Spectral type | A1 Van[4] |
U−B color index | +0.03[3] |
B−V color index | +0.02[3] |
Astrometry | |
Radial velocity (Rv) | −7.6±2.7[5] km/s |
Proper motion ( | RA: +10.17[2] mas/yr Dec.: +53.97[2] mas/yr |
Parallax ( | 18.95 ± 0.14 mas[2] |
Distance | 172 ± 1 ly (52.8 ± 0.4 pc) |
Absolute magnitude (MV) | 0.62[6] |
Details | |
Mass | 2.35[7] M☉ |
Radius | 2.8[1] R☉ |
Luminosity | 47.77[8] L☉ |
Surface gravity (log g) | 4.04[7] cgs |
Temperature | 9,911±337[7] K |
Rotation | 19 hours[1] |
Rotational velocity (v sin i) | 154[7] km/s |
Age | 327[7] Myr |
Other designations | |
Database references | |
SIMBAD | data |
Delta Ursae Minoris, Latinized from
Description[edit]
This is an A-type main-sequence star with a stellar classification of A1 Van,[4] where the 'n' indicates "nebulous" absorption lines in the spectrum due to rapid rotation. It is spinning with a projected rotational velocity of 180 km/s, which is giving the star an oblate shape with an equatorial bulge that is an estimated 7% larger than the polar radius.[13] The star is about 327[7] million years old with 2.35[7] times the mass of the Sun. It is radiating about 48[8] times the Sun's luminosity from its photosphere at an effective temperature of 9,911 K.[7]
Nomenclature[edit]
It bore the traditional name Yildun (also spelled Vildiur or Gildun) from the Turkish yıldız "star".[9] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[15] to catalogue and standardize proper names for stars. The WGSN approved the name Yildun for this star on 21 August 2016 and it is now so entered in the I
References[edit]
- ^ a b c Jim Kaler. "YILDUN (Delta Ursae Minoris)". Stars.astro.illinois.edu. Retrieved 2012-03-05.
- ^ a b c d e f van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600
- ^ a b c d Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
- ^ a b Gray, R. O.; Garrison, R. F. (December 1987), "The Early A-Type Stars: Refined MK Classification, Confrontation with Stroemgren Photometry, and the Effects of Rotation", Astrophysical Journal Supplement, 65: 581, Bibcode:1987ApJS...65..581G, doi:10.1086/191237.
- ^ a b de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
- ^ Jim Kaler. "The Polar Project". University of Illinois. Retrieved 2012-03-04.
- ^ a b c d e f g h David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
- ^ a b 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, S2CID 119257644.
- ^ a b Richard Hinckley Allen (1899). Star-names and Their Meanings. G.E. Stechert. pp. 447–460.
- ^ "del UMa". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-03-04.
- ^ a b "I
AU Catalog of Star Names". Retrieved 28 July 2016. - ^ Ridpath, Ian (1988), Star Tales, James Clarke & Co., p. 131, ISBN 0718826957.
- ^ Belle, G. T. (2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review, 20 (1): 51, arXiv:1204.2572, Bibcode:2012A&ARv..20...51V, doi:10.1007/s00159-012-0051-2, S2CID 119273474.
- ^ De Rosa, R. J.; Patience, J.; Wilson, P. A.; Schneider, A.; Wiktorowicz, S. J.; Vigan, A.; Marois, C.; Song, I.; MacIntosh, B.; Graham, J. R.; Doyon, R.; Bessell, M. S.; Thomas, S.; Lai, O. (2014). "The VAST Survey - III. The multiplicity of A-type stars within 75 pc". Monthly Notices of the Royal Astronomical Society. 437 (2): 1216. arXiv:1311.7141. Bibcode:2014MNRAS.437.1216D. doi:10.1093/mnras/stt1932. S2CID 88503488.
- ^ IAU Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016.
External links[edit]
- Delta Ursae Minoris on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen
α , X-Ray, Astrophoto, Sky Map, Articles and images