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Saiph

Coordinates: Sky map 05h 47m 45.4s, −09° 40′ 11″
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Saiph
Diagram showing star positions and boundaries of the Orion constellation and its surroundings
Location of Saiph (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Orion
Right ascension 05h 47m 45.38884s[1]
Declination −09° 40′ 10.5777″[1]
Apparent magnitude (V) 2.09[2]
Characteristics
Spectral type B0.5Iavar[3]
U−B color index –1.02[2]
B−V color index –0.18[2]
Variable type Slightly[4]
Astrometry
Radial velocity (Rv)+20.5[5] km/s
Proper motion (μ) RA: +1.46[1] mas/yr
Dec.: –1.28[1] mas/yr
Parallax (π)5.04 ± 0.22 mas[1]
Distance650 ± 30 ly
(198 ± 9 pc)
Absolute magnitude (MV)–6.1[6]
Details
Mass15.50 ± 1.25[7] M☉
Radius22.2[6] R☉
Luminosity56,881[7] L☉
Surface gravity (log g)2.9[6] cgs
Temperature26,500[6] K
Rotational velocity (v sin i)83[6] km/s
Age11.1 ± 0.5[8] Myr
Other designations
κ Orionis, 53 Orionis, 141 G. Orionis, BD–09 1235, FK5 220, HD 38771, HIP 27366, HR 2004, SAO 132542.[9]
Database references
SIMBADdata

Saiph (κ Orionis, 53 Orionis) is the sixth-brightest star in the constellation of Orion. Of the four bright stars that compose Orion's main quadrangle, it is the star at the south-eastern corner. A northern-hemisphere observer facing south would see it at the lower left of Orion, and a southern-hemisphere observer facing north would see it at the upper right. The name Saiph is from the Arabic saif al jabbar, 'سیف الجبّار' literally sword of the giant.[10] This name was originally applied to Eta Orionis.

In the 17th century catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Rekbah al Jauza al Yemeniat, which was translated into Latin as Genu Dextrum Gigantis "right knee of the giant".[11]

Parallax measurements yield an estimated distance of 650 light-years (198 parsecs) from Earth, which is about the same as Betelgeuse.[1] However despite being a hotter star, it is smaller and less luminous than Rigel with an apparent visual magnitude of 2.1.[2] The luminosity of this star changes slightly, varying by 0.04 magnitudes.[4]

Saiph has a stellar classification of B0.5 Ia. The luminosity class 'Ia' represents a bright supergiant star that has exhausted the supply of hydrogen at its core and evolved away from the main sequence. Saiph has a strong stellar wind and is losing mass at the rate of 9.0 × 10−7 times the mass of the Sun per year, or the equivalent of the Sun's mass every 1.1 million years.[6] Using a combination of parallax as determined by HIPPARCOS and spectrum yields a mass 15.50 ± 1.25 times and luminosity 56,881 times that of the Sun.[7] Analysis of the spectra and age of the members of the Orion OB1 association yields a 28 times that of the Sun (from an original mass 31.8 times that of the Sun) and an age of 6.2 million years.[12] Large stars such as Saiph (and many other stars in Orion) are destined to collapse on themselves and explode as Type II supernovae.[10]

Cultural significance

The Wardaman people of northern Australia know Saiph as the Guman digging stick, used to make a canyon by Black-headed Python.[13]

References

  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 Crawford, D. L.; Barnes, J. V.; Golson, J. C. (1971), "Four-color, H-beta, and UBV photometry for bright B-type stars in the northern hemisphere", The Astronomical Journal, 76: 1058, Bibcode:1971AJ.....76.1058C, doi:10.1086/111220
  3. ^ . Bibcode:1997A&A...323L..49P. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
  4. ^ a b Lefèvre, L.; et al. (November 2009), "A systematic study of variability among OB-stars based on HIPPARCOS photometry", Astronomy and Astrophysics, 507 (2): 11411201, Bibcode:2009A&A...507.1141L, doi:10.1051/0004-6361/200912304
  5. ^ Wielen, R.; et al. (1999), Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions, Astronomisches Rechen-Institut Heidelberg, Bibcode:1999VeARI..35....1W
  6. ^ a b c d e f Crowther, P. A.; Lennon, D. J.; Walborn, N. R. (January 2006), "Physical parameters and wind properties of galactic early B supergiants", Astronomy and Astrophysics, 446 (1): 279–293, arXiv:astro-ph/0509436, Bibcode:2006A&A...446..279C, doi:10.1051/0004-6361:20053685
  7. ^ a b c Hohle, M. M.; Neuhäuser, R.; Schutz, B. F. (April 2010), "Masses and luminosities of O- and B-type stars and red supergiants", Astronomische Nachrichten, 331 (4): 349, arXiv:1003.2335, Bibcode:2010AN....331..349H, doi:10.1002/asna.200911355
  8. ^ Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society, 410 (1): 190–200, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x{{citation}}: CS1 maint: unflagged free DOI (link)
  9. ^ "SAIPH -- Variable Star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2012-01-12
  10. ^ a b Kaler, James B., "SAIPH (Kappa Orionis)", Stars, University of Illinois, retrieved 2012-01-27
  11. ^ Knobel, E. B. (June 1895). "Al Achsasi Al Mouakket, on a catalogue of stars in the Calendarium of Mohammad Al Achsasi Al Mouakket". Monthly Notices of the Royal Astronomical Society. 55: 429. Bibcode:1895MNRAS..55..429K. doi:10.1093/mnras/55.8.429.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  12. ^ Voss, R.; Diehl, R.; Vink, J. S.; Hartmann, D. H. (2010). "Probing the evolving massive star population in Orion with kinematic and radioactive tracers". Astronomy and Astrophysics. 520: 10. Bibcode:2010A&A...520A..51V. doi:10.1051/0004-6361/201014408. A51.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  13. ^ Harney, Bill Yidumduma; Cairns, Hugh C. (2004) [2003]. Dark Sparklers (Revised ed.). Merimbula, New South Wales: Hugh C. Cairns. p. 139. ISBN 0-9750908-0-1.
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