Iota Orionis
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Orion |
| Right ascension | 05h 35m 25.98191s |
| Declination | −05° 54′ 35.6435″ |
| Apparent magnitude (V) | 2.77 |
| Characteristics | |
| ι Orionis A | |
| Spectral type | O9 III + B0.8 III/IV + B2:IV: |
| U−B color index | −1.08 |
| B−V color index | −0.24 |
| ι Orionis B | |
| Spectral type | B8 III |
| Variable type | Orion |
| Astrometry | |
| ι Orionis A | |
| Radial velocity (Rv) | 21.5 km/s |
| Proper motion (μ) | RA: +1.42 mas/yr Dec.: −0.46 mas/yr |
| Parallax (π) | 1.40±0.22 mas |
| Distance | 412+14 −13 pc |
| ι Orionis B | |
| Radial velocity (Rv) | 21.5 km/s |
| Proper motion (μ) | RA: +1.42 mas/yr Dec.: −0.46 mas/yr |
| Parallax (π) | 2.787 ± 0.0476 mas |
| Distance | 1,170 ± 20 ly (359 ± 6 pc) |
| Orbit | |
| Primary | ι Orionis Aa1 |
| Companion | ι Orionis Aa2 |
| Period (P) | 29.1338 days |
| Semi-major axis (a) | 132 R☉ |
| Eccentricity (e) | 0.764 |
| Inclination (i) | ~60° |
| Periastron epoch (T) | 2,450,072.80 HJD |
| Details | |
| ι Ori Aa1 | |
| Mass | 23.1 M☉ |
| Radius | 8.3 R☉ |
| Luminosity | 68,000 L☉ |
| Surface gravity (log g) | 3.73 cgs |
| Temperature | 32,500 K |
| Metallicity [Fe/H] | +0.10 dex |
| Rotational velocity (v sin i) | 122 km/s |
| Age | 4.0–5.5 Myr |
| ι Ori Aa2 | |
| Mass | 13.1 M☉ |
| Radius | 5.4 R☉ |
| Luminosity | 8,630 L☉ |
| Surface gravity (log g) | 3.78 cgs |
| Temperature | 27,000 K |
| Age | 9.4±1.5 Myr |
| ι Ori B | |
| Mass | 5.12 M☉ |
| Surface gravity (log g) | 4.0 cgs |
| Temperature | 18,000 K |
| Age | ~3 Myr |
| Other designations | |
| Hatysa, ι Orionis, Na'ir al Saif, BD−06°1241, FK5 209, SAO 132323, ADS 4193, WDS J05354-0555 | |
| ι Ori A: 44 Orionis, HD 37043, HIP 26241, HR 1899, 2MASS J05352597-0554357 | |
| ι Ori B: V2451 Ori, 2MASS J05352645-0554445 | |
| ι Ori C: 2MASS J05352920-0554471 | |
| Database references | |
| SIMBAD | ι Ori |
| ι Ori B | |
| ι Ori C | |
Iota Orionis (ι Orionis, abbreviated ι Ori) is a multiple star system in the equatorial constellation of Orion the hunter. It is the eighth-brightest member of Orion with an apparent visual magnitude of 2.77 and also the brightest member of the asterism known as Orion's Sword. It is a member of the NGC 1980 open cluster. From parallax measurements, it is located at a distance of roughly 1,340 light-years (412 parsecs) from the Sun.
The system has three visible components designated Iota Orionis A, B and C. Iota Orionis A has also been resolved using speckle interferometry and is also a massive spectroscopic binary, with components Iota Orionis Aa1 (officially named Hatysa /hɑːˈtiːsə/), Aa2, and Ab.