Alpha Pyxidis

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Alpha Pyxidis
Pyxis IAU.svg
Red circle.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 mas[1]
Distance880 ± 30 ly
(270 ± 10 pc)
Absolute magnitude (MV)−3.47[6]
Mass10.7[4] M
Radius6.3 ± 1.0[7] R
Luminosity10,000[4] L
Surface gravity (log g)3.63[8] cgs
Temperature24,300[8] K
Metallicity [Fe/H]−0.18[8] dex
Rotational velocity (v sin i)11[9] km/s
Other designations
Alpha Pyx, α Pyx, CPD−32° 2399, FK5 327, HD 74575, HIP 42828, HR 3468, SAO 199546[10]
Database references

Alpha Pyxidis, Latinised from α Pyxidis, 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][8] Stars such as this with more than 10 solar masses are expected to end their life by exploding as a supernova.[11]


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).[12]


  1. ^ a b c d e 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
  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. arXiv:0902.1314. Bibcode:2009AN....330..317H. doi:10.1002/asna.200811187. S2CID 17497112.
  5. ^ 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.
  6. ^ 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.
  7. ^ 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" (PDF), The Astrophysical Journal Letters, 726 (1): L5, arXiv:1012.3019, Bibcode:2011ApJ...726L...5H, doi:10.1088/2041-8205/726/1/L5, hdl:2268/81132, S2CID 119195567
  8. ^ 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.
  9. ^ 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. arXiv:0711.3783. Bibcode:2008A&A...481..199N. doi:10.1051/0004-6361:20078203. S2CID 10281324.
  10. ^ "alf Pyx". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-07-29.{{cite web}}: CS1 maint: postscript (link)
  11. ^ 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): 1652–1657. arXiv:astro-ph/0506708. Bibcode:2005AJ....130.1652R. doi:10.1086/444474. S2CID 119515135.
  12. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 17 日

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