Saiph

Saiph
Location of Saiph (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Orion
Right ascension 05h 47m 45.38884s[1]
Declination −09° 40′ 10.5777″[1]
Apparent magnitude (V) 2.09[2]
Characteristics
Evolutionary stage Blue supergiant
Spectral type B0.5 Ia[3]
U−B color index −1.02[2]
B−V color index −0.18[2]
Variable type Suspected[4]
Astrometry
Radial velocity (Rv)+20.5[5] km/s
Proper motion (μ) RA: +1.46[1] mas/yr
Dec.: −1.28[1] mas/yr
Parallax (π)5.04 ± 0.22 mas[1]
Distance650 ± 30 ly
(198 ± 9 pc)
Absolute magnitude (MV)−6.1[6]
Details
Mass15.5±1.25[7] or 21.1[8] M☉
Radius22.2[6] R☉
Luminosity56,881[7] L☉
Surface gravity (log g)2.9[6] cgs
Temperature26,500[6] K
Rotational velocity (v sin i)83[6] km/s
Age5.6[8] or 11.1±0.5[9] Myr
Other designations
κ Orionis, 53 Orionis, 141 G. Orionis, BD−09 1235, FK5 220, HD 38771, HIP 27366, HR 2004, SAO 132542.[10]
Database references
SIMBADdata

Saiph /ˈseɪf/, designation Kappa Orionis (κ Orionis, abbreviated Kappa Ori, κ Ori) and 53 Orionis (53 Ori), is a blue supergiant star and 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.[1] It is smaller, less luminous but hotter at its surface than Rigel with an apparent visual magnitude of 2.1.[2] The luminosity of this star changes slightly, varying by 0.04 magnitudes.[4]

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