Saiph (κ Orionis, 53 Orionis) 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. The name Saiph is from the Arabic saif al jabbar, 'سیف الجبّار' literally sword of the giant.[9]
With an apparent visual magnitude of 2.1,[2] parallax measurements yield an estimated distance of 650 light-years (198 parsecs) from Earth, which is about the same as Rigel.[1] It has a lower visual magnitude than Rigel because, although it is a much hotter star with a surface temperature of 26,500 K,[6] it emits most of its energy in the ultraviolet region of the spectrum, invisible to the human eye, paradoxically making it appear relatively dimmer.[9] The luminosity of this star changes slightly, varying by 0.04 magnitudes.[4]
Compared to the Sun this is an enormous star, with 14–17 times the mass and over 22 times the radius. It has a stellar classification of B0.5 Iab:.[3] The luminosity class 'Iab' represents a supergiant star that has exhausted the supply of hydrogen at its core and evolved away from the main sequence. However, the ':' indicates some uncertainty in the spectral value. Saiph has a strong stellar wind and is losing mass at the rate of 9.0 × 10–7 times the mass of the Sun per year, or the equivalent of the Sun's mass every 1.1 million years.[6] Large stars such as Saiph (and many other stars in Orion) are destined to collapse on themselves and explode as Type II supernovae.[9]
Excerpt from Wikipedia.