| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Orion |
| Right ascension | 05h 47m 45.4s |
| Declination | -09° 40′ 11″ |
| Apparent magnitude (V) | 2.06 |
| Characteristics | |
| Spectral type | B0.5 Iavar |
| U−B color index | -1.03 |
| B−V color index | -0.17 |
| Variable type | Slightly |
| Astrometry | |
| Radial velocity (Rv) | 21 km/s |
| Proper motion (μ) | RA: 1.55 mas/yr Dec.: -1.20 mas/yr |
| Parallax (π) | 4.52 ± 0.77 mas |
| Distance | approx. 700 ly (approx. 220 pc) |
| Absolute magnitude (MV) | -4.66 |
| Details | |
| Mass | 15-17 M☉ |
| Radius | 11 R☉ |
| Luminosity | 57,500 L☉ |
| Temperature | 26,000 K |
| Metallicity | ? |
| Rotation | ~82 km/s. |
| Age | ? years |
| Other designations | |
Kappa Orionis (κ Ori, κ Orionis, 53 Orionis) is the sixth-brightest star in the constellation of Orion. It has the traditional name Saiph. Of the four bright stars that compose Orion's main quadrangle, it is the star at the south-eastern corner. A northern-hemisphere observer facing south would see it at the lower left of Orion, and a southern-hemisphere observer facing north would see it at the upper right. The name Saiph is from the Arabic saif al jabbar, literally sword of the giant.
Kappa Orionis is the sixth brightest star in Orion. At 720 light years away and 15-17 solar masses, it is about the same distance away from the Sun, and about the same luminosity, as Rigel. It has a much higher magnitude value (2.06) than Rigel because, although it is a much hotter star with a surface temperature of 26,000 K, it emits most of its energy in the ultraviolet region of the spectrum, invisible to the human eye, paradoxically making it appear relatively dimmer. Large stars such as Saiph (and many other stars in Orion) are destined to collapse on themselves and explode as supernovae.
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