Kappa Orionis

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**Kappa Orionis**
Observation data Epoch J2000
Constellation (pronunciation)	Orion
Right ascension	05^h 47^m 45.4^s
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 (R_v)	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 (M_V)	-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
Saiph, 53 Orionis, HR 2004, BD -09°1235, HD 38771, SAO 132542, FK5 220, HIP 27366.

Kappa Orionis (κ Ori / κ Orionis / 53 Orionis) is the sixth-brightest star in the constellation of Orion. It also has the traditional name Saiph. To an observer in the northern hemisphere facing south, it is the lower left of the four bright stars that compose Orion's main quadrangle. The name 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 size, as Rigel. It has a much higher magnitude (2.06) than Rigel because it is a much hotter star, with a surface temperature of 26,000,000 degrees Fahrenheit. Such stars mostly radiate ultraviolet light. Large stars such as Saiph (and many other stars in Orion) are destined to collapse on themselves and explode as supernovae.