Zeta Orionis
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| Observation data Epoch J2000 |
|
|---|---|
| Constellation | Orion |
| Right ascension | 05h 40m 45.5s |
| Declination | −01° 56′ 34″ |
| Apparent magnitude (V) | 1.70/~4/4.21 |
| Spectral Characteristics | |
| Spectral type | O9 Iab/O/B0 III |
| U-B color index | −1.07 |
| B-V color index | 0.14 / ? / −0.01 |
| Variable type | |
| Astrometry | |
| Radial velocity (Rv) | 18 km/s |
| Proper motion (μ) | RA: 3.99 mas/yr Dec.: 2.54 mas/yr |
| Parallax (π) | 3.99 ± 0.79 mas |
| Distance | approx. 800 ly (approx. 250 pc) |
| Absolute magnitude (MV) | −5.25/−3/−2.8 |
| Visual binary orbit | |
| Companion | Zeta Orionis B |
| Period (P) | 1,500 years |
| Semimajor axis (a) | 2.728" |
| Eccentricity (e) | 0.07 |
| Inclination (i) | 72.0° |
| Node (Ω) | 155.5° |
| Periastron epoch (T) | 2070.6 |
| Physical Characteristics | |
| Mass | 28/23/? M☉ |
| Radius | 20/? R☉ |
| Luminosity | 100,000/1,300/? L☉ |
| Temperature | 30,000/?/24,000 K |
| Metallicity | ? |
| Rotation | 140 km/s / ? |
| Age | ? years |
| Other designations | |
| Database references | |
| SIMBAD | data |
Zeta Orionis (ζ Ori) is a star in the constellation Orion. It also has the traditional name Alnitak. The name is taken from the Arabic an-nitaq, "the belt".
Alnitak is a triple star system at the eastern end of Orion's belt. The primary is a blue supergiant that is also a close binary. The Alnitak system is bathed in the nebulosity of IC 434.
[edit] In fiction
The City on the Edge of Forever, an episode of Star Trek: The Original Series, Kirk mentions that in the year 2030 there is a famous novelist from "a planet circling the far left star in Orion's Belt".
[edit] References
- C. A. Hummel et al, "ζ Orionis A Is a Double Star", The Astrophysical Journal, volume 540, 2, 2000.
[edit] External links
- Alnitak 3. SolStation. Retrieved on December 15, 2005.
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