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] cgs |
| 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] cgs |
| Temperature | 27,000[3] K |
| Age | 9.4 ± 1.5[3] Myr |
| Other designations | |
Iota Orionis (ι Ori, ι Orionis) is a star in the equatorial constellation of Orion the hunter. The apparent visual magnitude of Iota Orionis is 2.77,[2] making it the eighth brightest member of Orion. It is the brightest star in an asterism known as Orion's sword. Iota Orionis has the traditional names Hatsya or Hatysa[7][8] and in Arabic, Na’ir al Saif, which means simply "the Bright One of the Sword."[9] From parallax measurements, it is located at a distance of roughly 1,330 light-years (410 parsecs) from Earth.[1]
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 stellar 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]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 2.0 2.1 2.2 2.3 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found. Kunitzsch traces the name to Becvar's Atlas Coeli (1951), where it appeared as "Hatysa", but was unable to find an older source.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
External links
- Iota Orionis by Dr. Jim Kaler.
- David Darling's encyclopedia entry
