Eta Orionis
| |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Orion |
| Right ascension | 05h 24m 28.61672s[1] |
| Declination | –02° 23′ 49.7311″[1] |
| Apparent magnitude (V) | 3.42[2] |
| Characteristics | |
| Spectral type | B1 V + B3 V + B2 V[3] |
| U−B color index | –0.90[2] |
| B−V color index | −0.17[2] |
| Variable type | Algol[4] |
| Astrometry | |
| Radial velocity (Rv) | +19.8[5] km/s |
| Proper motion (μ) | RA: −0.71[1] mas/yr Dec.: −3.46[1] mas/yr |
| Parallax (π) | 3.34 ± 1.07[1] mas |
| Distance | approx. 1,000 ly (approx. 300 pc) |
| Details | |
| η Ori A | |
| Mass | 20 M☉ |
| Radius | 10 R☉ |
| Luminosity | 38,000 L☉ |
| Rotational velocity (v sin i) | 60[6] km/s |
| η Ori B | |
| Rotational velocity (v sin i) | 45[6] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
Eta Orionis (η Ori, η Orionis) is a star in the constellation Orion. Other names are Saiph[8] (Arabic for "sword"), Algjebbah[9] (Arabic for "scutum"), and Ensis (Latin for "sword", since the star is taken to represent Orion's sheathed weapon). 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.[3]
See also
References
- 1 2 3 4 5 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752
, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357 - 1 2 3 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
- 1 2 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:0907.5172, 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, retrieved 2009-09-10
- 1 2 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.