Alpha Pyxidis

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

Location of α Pyxidis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Pyxis
Right ascension 08h 43m 35.53756s[1]
Declination –33° 11′ 10.9898″[1]
Apparent magnitude (V) 3.67[2]
Spectral type B1.5III[3]
U−B color index –0.84[2]
B−V color index –0.19[2]
Variable type Beta Cephei[4]
Radial velocity (Rv) +15.3[5] km/s
Proper motion (μ) RA: –14.27[1] mas/yr
Dec.: +10.43[1] mas/yr
Parallax (π) 3.71 ± 0.14[1] mas
Distance 880 ± 30 ly
(270 ± 10 pc)
Mass 10.7[4] M
Radius 6.3 ± 1.0[6] R
Luminosity 10,000[4] L
Surface gravity (log g) 3.63[7] cgs
Temperature 24,300[7] K
Metallicity [Fe/H] -0.18[7] dex
Rotational velocity (v sin i) 11[8] km/s
Other designations
α Pyxidis, CPD−32° 2399, FK5 327, HD 74575, HIP 42828, HR 3468, SAO 199546.[9]
Database references

Alpha Pyxidis (Alpha Pyx, α Pyxidis, α Pyx) is a giant star in the constellation Pyxis. It has a stellar classification of B1.5III and is a Beta Cephei variable. This star has more than ten times the mass of the Sun and is more than six times the Sun's radius. The surface temperature is 24,300 K and the star is about 10,000 times as luminous as the Sun.[3][4][7] Stars such as this with more than 10 solar masses are expected to end their life by exploding as a supernova.[10]


In Chinese, 天狗 (Tiān Gǒu), meaning Celestial Dog, refers to an asterism consisting of α Pyxidis, e Velorum, f Velorum, β Pyxidis, γ Pyxidis and δ Pyxidis. Consequently, α Pyxidis itself is known as 天狗五 (Tiān Gǒu wǔ, English: the Fifth Star of Celestial Dog.)[11]


  1. ^ a b c d e van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752Freely accessible, doi:10.1051/0004-6361:20078357 
  2. ^ a b c Fernie, J. D. (May 1983). "New UBVRI photometry for 900 supergiants". Astrophysical Journal Supplement Series. 52: 7–22. Bibcode:1983ApJS...52....7F. doi:10.1086/190856. 
  3. ^ a b Hiltner, W. A.; Garrison, R. F.; Schild, R. E. (July 1969). "MK Spectral Types for Bright Southern OB Stars". Astrophysical Journal. 157: 313. Bibcode:1969ApJ...157..313H. doi:10.1086/150069. 
  4. ^ a b c d Hubrig, S.; et al. (January 2009). "New magnetic field measurements of beta Cephei stars and Slowly Pulsating B stars". Astronomische Nachrichten. 330 (4): 317. Bibcode:2009AN....330..317H. arXiv:0902.1314Freely accessible. doi:10.1002/asna.200811187. 
  5. ^ Wilson, R. E. (1953). General Catalogue of Stellar Radial Velocities. Carnegie Institute of Washington D.C. Bibcode:1953GCRV..C......0W. 
  6. ^ Hubrig, S.; Ilyin, I.; Schöller, M.; Briquet, M.; Morel, T.; De Cat, P. (January 2011), "First Magnetic Field Models for Recently Discovered Magnetic β Cephei and Slowly Pulsating B Stars", The Astrophysical Journal Letters, 726 (1): L5, Bibcode:2011ApJ...726L...5H, arXiv:1012.3019Freely accessible, doi:10.1088/2041-8205/726/1/L5 
  7. ^ a b c d Kilian, J. (February 1994). "Chemical abundances in early B-type stars. 5: Metal abundances and LTE/NLTE comparison". Astronomy and Astrophysics. 282 (3): 867–873. Bibcode:1994A&A...282..867K. 
  8. ^ Nieva, M. F.; Przybilla, N. (April 2008). "Carbon abundances of early B-type stars in the solar vicinity. Non-LTE line-formation for C II/III/IV and self-consistent atmospheric parameters". Astronomy and Astrophysics. 481 (1): 199–216. Bibcode:2008A&A...481..199N. arXiv:0711.3783Freely accessible. doi:10.1051/0004-6361:20078203. 
  9. ^ "NSV 4220 -- Variable Star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2010-02-23. 
  10. ^ Reed, B. Cameron (June 28, 2005). "New Estimates of the Solar-Neighborhood Massive-Stars Birthrate and the Galactic Supernova Rate". The Astronomical Journal. 130 (4): 1652. Bibcode:2005AJ....130.1652R. arXiv:astro-ph/0506708Freely accessible. doi:10.1086/444474. 
  11. ^ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 17 日

External links[edit]

  • Kaler, James. "Alpha Pyxidis". University of Illinois. Retrieved 2010-02-23.