Iota Orionis
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Orion |
| Right ascension | 05h 35m 25.98191s[1] |
| Declination | –05° 54′ 35.6435″[1] |
| Apparent magnitude (V) | 2.77[2] |
| Characteristics | |
| Spectral type | O9 III + B0.8 III/IV[3] |
| U−B color index | –1.08[2] |
| B−V color index | –0.24[2] |
| Astrometry | |
| Radial velocity (Rv) | 21.5[4] km/s |
| Proper motion (μ) | RA: +1.42[1] mas/yr Dec.: –0.46[1] mas/yr |
| Parallax (π) | 1.40 ± 0.22[1] mas |
| Distance | approx. 2,300 ly (approx. 700 pc) |
| Orbit[3] | |
| Period (P) | 29.1338 days |
| Eccentricity (e) | 0.764 |
| Periastron epoch (T) | 2,450,072.80 HJD |
| Details | |
| ι Ori A | |
| Surface gravity (log g) | 3.73[3] |
| Temperature | 32,500[3] K |
| Metallicity [Fe/H] | +0.10[5] dex |
| Rotational velocity (v sin i) | 122[6] km/s |
| Age | 4.0–5.5[3] Myr |
| ι Ori B | |
| Surface gravity (log g) | 3.78[3] |
| Temperature | 27,000[3] K |
| Age | 9.4 ± 1.5[3] Myr |
| Other designations | |
Iota Orionis (ι Ori, ι Orionis) is the brightest star in Orion's sword, and is located at the tip of the sword. It has the traditional names Hatsya (sometimes with the typographic error Hatysa), or in Arabic, Na’ir al Saif, which means simply "the Bright One of the Sword."+-9*
Iota Orionis is a quadruple system dominated by a massive spectroscopic binary with an eccentric (e=0.764), 29-day orbit. The binary is composed of a class O9 III star (blue giant) and a class B0.8 III/IV star, with the secondary being about 2 magnitudes fainter.[3] The collision of the stellar winds from this pair makes the system a strong X-ray source. Oddly, the two objects of this system appear to have different ages, with the secondary being about double the age of the primary. In combination with the high eccentricity of their orbit, this suggests that the binary system was created through a capture, rather than by being formed together and undergoing a mass transfer. This capture may have occurred, for example, through an encounter between two binary systems.[3]
[edit] References
- ^ a b c d e van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, Bibcode 2007A&A...474..653V, doi:10.1051/0004-6361:20078357
- ^ a b c Nicolet, B. (1978). "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System". Astronomy and Astrophysics Supplement Series 34: 1–49. Bibcode 1978A&AS...34....1N.
- ^ a b c d e f g h i j Bagnuolo et al. (June 2001), "ι Orionis-Evidence for a Capture Origin Binary", The Astrophysical Journal 554 (1): 362–367, Bibcode 2001ApJ...554..362B, doi:10.1086/321367
- ^ Evans, D. S. (June 20–24, 1966), Batten, Alan Henry; Heard, John Frederick, ed., The Revision of the General Catalogue of Radial Velocities, University of Toronto: International Astronomical Union, http://adsabs.harvard.edu/abs/1967IAUS...30...57E, retrieved 2009-09-10
- ^ Conti, P. S.; Loonen, J. P. (October 1970), "Coarse analysis of the helium weak B star Iota Ori B", Astronomy and Astrophysics 8: 197–203, Bibcode 1970A&A.....8..197C
- ^ Uesugi, Akira; Fukuda, Ichiro (1970), "Catalogue of rotational velocities of the stars", Contributions from the Institute of Astrophysics and Kwasan Observatory (University of Kyoto), Bibcode 1970crvs.book.....U
[edit] External links
- Iota Orionis by Dr. Jim Kaler.
- David Darling's encyclopedia entry
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