Saiph
Saiph /ˈseɪf/, designation Kappa Orionis (κ Orionis, abbreviated Kappa Ori, κ Ori) and 53 Orionis (53 Ori), is the sixth-brightest star in the constellation of Orion. 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. Parallax measurements yield an estimated distance of 650 light-years (200 parsecs) from the Sun, which is about the same as Betelgeuse. It is smaller, less luminous but hotter at its surface than Rigel with an apparent visual magnitude of 2.1. The luminosity of this star changes slightly, varying by 0.04 magnitudes.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Orion |
| Right ascension | 05h 47m 45.38884s |
| Declination | −09° 40′ 10.5777″ |
| Apparent magnitude (V) | 2.09 |
| Characteristics | |
| Spectral type | B0.5 Ia |
| U−B color index | −1.02 |
| B−V color index | −0.18 |
| Variable type | Suspected |
| Astrometry | |
| Radial velocity (Rv) | +20.5 km/s |
| Proper motion (μ) | RA: +1.46 mas/yr Dec.: −1.28 mas/yr |
| Parallax (π) | 5.04 ± 0.22 mas |
| Distance | 650 ± 30 ly (198 ± 9 pc) |
| Absolute magnitude (MV) | −6.1 |
| Details | |
| Mass | 15.50±1.25 M☉ |
| Radius | 22.2 R☉ |
| Luminosity | 56,881 L☉ |
| Surface gravity (log g) | 2.9 cgs |
| Temperature | 26,500 K |
| Rotational velocity (v sin i) | 83 km/s |
| Age | 11.1±0.5 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |