Alpha Pyxidis

Alpha Pyxidis
Diagram showing star positions and boundaries of the Pyxis constellation and its surroundings


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]
Characteristics
Spectral type B1.5III[3]
U−B color index –0.84[2]
B−V color index –0.19[2]
Variable type Beta Cephei[4]
Astrometry
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
Distance880 ± 30 ly
(270 ± 10 pc)
Details
Mass10.7[4] M☉
Radius6.3 ± 1.0[6] R☉
Luminosity10,000[4] L☉
Surface gravity (log g)3.63[7] cgs
Temperature24,300[7] K
Metallicity [Fe/H]-0.18[7] dex
Rotational velocity (v sin i)11[8] km/s
Other designations
α Pyxidis, α Pyx, Alpha Pyx, CPD−32  2399, FK5 327, HD 74575, HIP 42828, HR 3468, SAO 199546.[9]

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]

Naming

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]

References

  1. 1 2 3 4 5 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 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. 1 2 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. 1 2 3 4 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:0902.1314Freely accessible. Bibcode:2009AN....330..317H. 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, arXiv:1012.3019Freely accessible, Bibcode:2011ApJ...726L...5H, doi:10.1088/2041-8205/726/1/L5
  7. 1 2 3 4 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. arXiv:0711.3783Freely accessible. Bibcode:2008A&A...481..199N. 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. arXiv:astro-ph/0506708Freely accessible. Bibcode:2005AJ....130.1652R. 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

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