Alpha Columbae

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Alpha Columbae
Diagram showing star positions and boundaries of the Columba constellation and its surroundings
Cercle rouge 100%.svg

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
Distance 261 ± 8 ly
(80 ± 2 pc)
Absolute magnitude (MV) −1.9
Details
Mass 4.5[6] M
Radius 5.8[7] R
Luminosity (bolometric) 1,000[6] L
Surface gravity (log g) 3.73[7] cgs
Temperature 12,963[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
SIMBAD data

Alpha Columbae (α Columbae, α Col) is the Bayer designation for a third magnitude star in the southern constellation of Columba. It has the traditional name of Phact, which is derived from the Arabic term for "ring dove". 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]

Properties[edit]

This is believed to be a solitary star,[10][8] although it has a faint optical companion at an angular separation of 13.5 arcseconds, making it a double star.[11] 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.[12] 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.

Etymology[edit]

The proper name "Phact" (also Phad, Phaet, Phakt[12]) derived from the Arabic ألفاجتة - fākh(i)tah [fa:x(i)ta] which meaning "ring dove". It was originally applied to the constellation Cygnus as al-Fākhtah, but later transferred to this star.[13][14][15][16] The etymology of its name hadāri (unknown meaning)[17] has also been suggested.

In Chinese, 丈人 (Zhàng Rén), meaning Grandfather, refers to an asterism consisting of α Columbae and ε Columbae.[18] Consequently, α Columbae itself is known as 丈人一 (Zhàng Rén yī, English: the First Star of Grandfather.).[19] From this Chinese name, the name Chang Jin was appeared[20]

References[edit]

  1. ^ 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 
  2. ^ a b c d Cousins, A. W. J. (1972), UBV Photometry of Some Very Bright Stars, Monthly Notes of the Astronomical Society, Southern Africa 31: 69, Bibcode:1972MNSSA..31...69C 
  3. ^ a b 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. ^ a b Jim Kaler: Phact - STARS. Accessed on line April 21, 2009.
  7. ^ a b c 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:0908.1239, Bibcode:2009A&A...505..687M, doi:10.1051/0004-6361/200911960 
  8. ^ a b c Oudmaijer, R. D. et al. (October 2008), Sub-milliarcsecond precision spectro-astrometry of Be stars, Astronomy and Astrophysics 489 (2): 627–631, arXiv:0807.3673, 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. ^ 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:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. 
  11. ^ 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.
  12. ^ a b 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.
  13. ^ Davis, Jr., G. A., (1971). Pronunciations, Derivations, and Meanings of a Selected List of Star Names (rep. ed.). Cambridge, MA: Sky Pub. Corp. p. 11. 
  14. ^ Kunitzsch, P., (1959). Arabische Sternnamen in Europa. Wiesbaden: Otto Harrassowitz. pp. 191–192. 
  15. ^ 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. 
  16. ^ 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. 
  17. ^ Allen, R. H., (1963). Star Names: Their Lore and Meaning (rep. ed.). New York, NY: Dover Publications Inc. p. 167. ISBN 0-486-21079-0. 
  18. ^ (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.
  19. ^ (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.
  20. ^ Richard Hinckley Allen: Star Names — Their Lore and Meaning: Columbae