Alpha Columbae

Alpha Columbae
Diagram showing star positions and boundaries of the Columba constellation and its surroundings


Location of α Columbae (circled)

Observation data
Epoch J2000.0      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 B7 IV[3]
U−B color index −0.44[2]
B−V color index −0.125[2]
R−I color index −0.09[4]
Astrometry
Radial velocity (Rv)+35.0[5] 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)−1.9
Details
Mass4.5[6] M☉
Radius5.8[7] R☉
Luminosity (bolometric)1,000[6] L☉
Surface gravity (log g)3.73[7] cgs
Temperature12,963[7] K
Rotational velocity (v sin i)176[8] km/s
Other designations
Alpha Columbae, α Col, CCDM J05396−3404 A, CD−34 2375, CPD−34 703, FK5 215, GC 7078, HD 37795, HIP 26634, HR 1956, NSV 2549, PPM 281732, SAO 196059.[9]
Database references
SIMBADdata

Alpha Columbae (α Columbae, abbreviated Alpha Col, α Col), also named Phact,[10] 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

Alpha Columbae is the star's Bayer designation.

The traditional name of Phact (also Phad, Phaet, Phakt[11]) derives from the Arabic ألفاجتة - fākh(i)tah [fa:x(i)ta] meaning 'ring dove'. It was originally applied to the constellation Cygnus as al-Fākhtah, but later transferred to this star.[12][13][14][15] The etymology of its name hadāri (unknown meaning)[16] has also been suggested. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[17] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[18] 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.[19] Consequently, α Columbae itself is known as 丈人一 (Zhàng Rén yī, English: the First Star of Grandfather.).[20] From this Chinese name, the name Chang Jin has appeared[21]

Properties

This is believed to be a solitary star,[8][22] although it has a faint optical companion at an angular separation of 13.5 arcseconds, making it a double star.[23] The stellar classification of Alpha Columbae is B7 IV,[3] with the luminosity class of IV indicating it has evolved into a subgiant 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.[11] 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.[8] It is a suspected Gamma Cassiopeiae type (GCAS) variable star, with its apparent magnitude varying from 2.62m to 2.66m.

References

  1. 1 2 3 4 5 6 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357
  2. 1 2 3 4 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. 1 2 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:1982MSS...C03....0H
  4. ↑ 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.
  5. ↑ Wilson, R. E. (1953). General Catalogue of Stellar Radial Velocities. Carnegie Institute of Washington D.C. Bibcode:1953GCRV..C......0W.
  6. 1 2 Jim Kaler: Phact - STARS. Accessed on line April 21, 2009.
  7. 1 2 3 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, arXiv:0908.1239Freely accessible, Bibcode:2009A&A...505..687M, doi:10.1051/0004-6361/200911960
  8. 1 2 3 Oudmaijer, R. D.; et al. (October 2008), "Sub-milliarcsecond precision spectro-astrometry of Be stars", Astronomy and Astrophysics, 489 (2): 627–631, arXiv:0807.3673Freely accessible, Bibcode:2008A&A...489..627O, doi:10.1051/0004-6361:20079117
  9. ↑ * alf Col -- Be Star, database entry, SIMBAD. Accessed on line April 21, 2009.
  10. ↑ "IAU Catalog of Star Names". Retrieved 28 July 2016.
  11. 1 2 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.
  12. ↑ Davis, Jr. G. A. (1971). Pronunciations, Derivations, and Meanings of a Selected List of Star Names (Reprint ed.). Cambridge, MA: Sky Pub. Corp. p. 11.
  13. ↑ Kunitzsch, P. (1959). Arabische Sternnamen in Europa. Wiesbaden: Otto Harrassowitz. pp. 191–192.
  14. ↑ 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.
  15. ↑ 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.
  16. ↑ Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York, NY: Dover Publications Inc. p. 167. ISBN 0-486-21079-0.
  17. ↑ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  18. ↑ "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016.
  19. ↑ (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.
  20. ↑ (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.
  21. ↑ Richard Hinckley Allen: Star Names — Their Lore and Meaning: Columbae
  22. ↑ 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. arXiv:0806.2878Freely accessible. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x.
  23. ↑ 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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