Astronomy:Alpha Columbae

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Short description: Star in the constellation Columba
Alpha Columbae
Columba IAU.svg
Red circle.svg
Location of α Columbae (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Columba
Right ascension  05h 39m 38.94103s[1]
Declination −34° 04′ 26.7950″[1]
Apparent magnitude (V) 2.645[2]
Characteristics
Spectral type B9Ve[3] or B7 IV[4]
U−B color index −0.44[2]
B−V color index −0.125[2]
R−I color index −0.09[5]
Astrometry
Radial velocity (Rv)+35.0[6] km/s
Proper motion (μ) RA: −1.58[1] mas/yr
Dec.: −24.82[1] mas/yr
Parallax (π)12.48 ± 0.36[1] mas
Distance261 ± 8 ly
(80 ± 2 pc)
Absolute magnitude (MV)−1.87[7]
Details
Mass4.5[8] M☉
Radius5.8[9] R☉
Luminosity (bolometric)1,000[8] L☉
Surface gravity (log g)3.73[9] cgs
Temperature12,963[9] K
Rotational velocity (v sin i)176[10] km/s
Age93[3] Myr
Other designations
Alpha Col, α Col, NSV 2549, CD−34 2375, CPD−34 703, FK5 215, GC 7078, HD 37795, HIP 26634, HR 1956, SAO 196059, PPM 281732, CCDM  J05396−3404 A[11]
Database references
SIMBADdata

Alpha Columbae or α Columbae, officially named Phact (/ˈfækt/),[12][13] is a third magnitude star in the southern constellation of Columba. It has an apparent visual magnitude of 2.6,[2] making it the brightest member of Columba. Based upon parallax measurements made during the Hipparcos mission, Alpha Columbae is located at a distance of around 261 light-years (80 parsecs).[1]

Nomenclature

α Columbae, Latinized to Alpha Columbae, is the star's Bayer designation.

The traditional name of Phact (also rendered Phad, Phaet, Phakt)[14] derives from the Arabic فاختة fākhitah 'ring dove'. It was originally applied to the constellation Cygnus and later transferred to this star.[15][16][17][18] The etymology of its name hadāri (unknown meaning)[19] has also been suggested. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[20] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[21] included a table of the first two batches of names approved by the WGSN; which included Phact for this star.

In Chinese, 丈人 (Zhàng Rén), meaning Grandfather, refers to an asterism consisting of α Columbae and ε Columbae.[22] Consequently, α Columbae itself is known as 丈人一 (Zhàng Rén yī, English: the First Star of Grandfather.).[23] From this Chinese name, the name Chang Jin has appeared[24]

Properties

This is believed to be a solitary star,[10][25] although it has a faint optical companion at an angular separation of 13.5 arcseconds, making it a double star.[26] The stellar classification of Alpha Columbae is B9Ve,[3] matching a B-type main-sequence star. The spectrum shows it to be a Be star surrounded by a hot gaseous disk, which is generating emission lines because of hydrogen recombination.[14] Like most if not all such stars, it is rotating rapidly with a projected rotational velocity of 176 km s−1. The azimuthal equatorial velocity may be 457 km s−1.[10] It is a suspected Gamma Cassiopeiae type (GCAS) variable star, with its apparent magnitude varying from 2.62m to 2.66m.

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V 
  2. ↑ 2.0 2.1 2.2 2.3 Cousins, A. W. J. (1972), "UBV Photometry of Some Very Bright Stars", Monthly Notes of the Astronomical Society of Southern Africa 31: 69, Bibcode: 1972MNSSA..31...69C 
  3. ↑ 3.0 3.1 3.2 Levenhagen, R. S.; Leister, N. V. (2006), "Spectroscopic analysis of southern B and Be stars", Monthly Notices of the Royal Astronomical Society 371 (1): 252–262, doi:10.1111/j.1365-2966.2006.10655.x, Bibcode: 2006MNRAS.371..252L. 
  4. ↑ Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, 3, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode: 1982mcts.book.....H 
  5. ↑ HR 1956, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line April 21, 2009.
  6. ↑ Wilson, R. E. (1953). "General Catalogue of Stellar Radial Velocities". Carnegie Institute Washington D.C. Publication (Carnegie Institute of Washington D.C.). Bibcode: 1953GCRV..C......0W. 
  7. ↑ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A. 
  8. ↑ 8.0 8.1 Jim Kaler: Phact - STARS . Accessed on line April 21, 2009.
  9. ↑ 9.0 9.1 9.2 Meilland, A.; Stee, Ph.; Chesneau, O.; Jones, C. (October 2009), "VLTI/MIDI observations of 7 classical Be stars", Astronomy and Astrophysics 505 (2): 687–693, doi:10.1051/0004-6361/200911960, Bibcode: 2009A&A...505..687M 
  10. ↑ 10.0 10.1 10.2 Oudmaijer, R. D. et al. (October 2008), "Sub-milliarcsecond precision spectro-astrometry of Be stars", Astronomy and Astrophysics 489 (2): 627–631, doi:10.1051/0004-6361:20079117, Bibcode: 2008A&A...489..627O 
  11. ↑ "alf Col". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=alf+Col. 
  12. ↑ Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7. 
  13. ↑ "IAU Catalog of Star Names". http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt. Retrieved 28 July 2016. 
  14. ↑ 14.0 14.1 Note of HR 1956, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line April 21, 2009.
  15. ↑ Davis, Jr. G. A. (1971). Pronunciations, Derivations, and Meanings of a Selected List of Star Names (Reprint ed.). Cambridge, Massachusetts: Sky Pub. Corp. p. 11. 
  16. ↑ Kunitzsch, P. (1959). Arabische Sternnamen in Europa. Wiesbaden: Otto Harrassowitz. pp. 191–192. 
  17. ↑ Laffitte, R. (2005). Héritages arabes: Des noms arabes pour les étoiles (2éme revue et corrigée ed.). Paris: Librairie Orientaliste Paul Geunthner / Les Cahiers de l'Orient. p. 223. 
  18. ↑ Kunitzsch, P.; Smart, T. (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, MA: Sky Pub. p. 30. ISBN 978-1-931559-44-7. 
  19. ↑ Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York City , NY: Dover Publications Inc.. p. 167. ISBN 0-486-21079-0. 
  20. ↑ "IAU Working Group on Star Names (WGSN)". https://www.iau.org/science/scientific_bodies/working_groups/280/. Retrieved 22 May 2016. 
  21. ↑ "Bulletin of the IAU Working Group on Star Names, No. 1". http://www.pas.rochester.edu/~emamajek/WGSN/WGSN_bulletin1.pdf. Retrieved 28 July 2016. 
  22. ↑ (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN:978-986-7332-25-7.
  23. ↑ (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 , Hong Kong Space Museum. Accessed on line November 23, 2010.
  24. ↑ Richard Hinckley Allen: Star Names — Their Lore and Meaning: Columbae
  25. ↑ Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society 389 (2): 869–879. doi:10.1111/j.1365-2966.2008.13596.x. Bibcode: 2008MNRAS.389..869E. 
  26. ↑ CCDM J05396-3404, database entry, J. Dommanget and O. Nys (2002) Catalogue of the Components of Double and Multiple Stars, Accessed on line April 21, 2009.



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