Epoch J2000 Equinox J2000
|Right ascension||05h 24m 28.61672s|
|Declination||–02° 23′ 49.7311″|
|Apparent magnitude (V)||3.42|
|Spectral type||B1 V + B3 V + B2 V|
|U−B color index||–0.90|
|B−V color index||−0.17|
|Radial velocity (Rv)||+19.8 km/s|
|Proper motion (μ)||RA: −0.71 mas/yr
Dec.: −3.46 mas/yr
|Parallax (π)||3.34 ± 1.07 mas|
|Distance||approx. 1,000 ly
(approx. 300 pc)
|η Ori A|
|Mass||20 M☉|
|Radius||10 R☉|
|Luminosity||38,000 L☉|
|Rotational velocity (v sin i)||60 km/s|
|η Ori B|
|Rotational velocity (v sin i)||45 km/s|
Eta Orionis (η Ori, η Orionis) is a star in the constellation Orion. Other names are Saiph (Arabic for "sword") and Algjebbah (Arabic for "scutum"). Eta Orionis lies a little to the west of Orion's belt between Delta Orionis and Rigel, being closer to Delta Orionis than to Rigel. It lies at a distance of around 1,000 light years from Earth and is part of the Orion Arm.
This is a quadruple star system, of which three members can be resolved with a telescope. The primary component is an eclipsing binary star in a triple-star grouping. These stars have orbital periods of 8 days and 9.2 years. It includes a variable star with a pulsation period of around 8 hours. Three of the components are B-type main sequence stars with stellar classifications of B1 V, B3 V and B2 V.
- van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv: , Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357
- 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
- Zasche, P.; et al. (August 2009), "A Catalog of Visual Double and Multiple Stars With Eclipsing Components", The Astronomical Journal, 138 (2): 664–679, arXiv: , Bibcode:2009AJ....138..664Z, doi:10.1088/0004-6256/138/2/664
- AAVSO International Variable Star Index VSX (Watson+, 2006-2012) VizieR
- Evans, D. S. (June 20–24, 1966). Batten, Alan Henry; Heard, John Frederick, eds. The Revision of the General Catalogue of Radial Velocities. University of Toronto: International Astronomical Union. Bibcode:1967IAUS...30...57E.
- Levato, H. (January 1975), "Rotational velocities and spectral types for a sample of binary systems", Astronomy and Astrophysics Supplement Series, 19: 91–99, Bibcode:1975A&AS...19...91L
- "CCDM J05245-0223AB -- Double or multiple star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2012-02-09
- Allen, R. H. (1899). Star-Names and Their Meanings. New York: G. E. Stechert. p. 316.
Saiph was also used to indicate Kappa Orionis in the same constellation.
- Moore, P. (1983). The Guinness Book of Astronomy: Facts and Feats (2nd ed.). Middlesex: Guinness Superlatives Limited. p. 230.
|This binary or multiple star system-related article is a stub. You can help Wikipedia by expanding it.|