Xi Persei (ξ Persei, abbreviated Xi Per, ξ Per), formally named Menkib //, is a star in the constellation of Perseus. Based upon parallax measurements taken during the Hipparcos mission, it is approximately 1,200 light-years from the Sun.
Epoch J2000 Equinox J2000
|Right ascension||03h 58m 57.90229s|
|Declination||+35° 47′ 27.7132″|
|Apparent magnitude (V)||4.04|
|U−B color index||−0.93|
|B−V color index||+0.02|
|Variable type||slightly variable|
|Radial velocity (Rv)||65.40 km/s|
|Proper motion (μ)|| RA: 3.62 mas/yr |
Dec.: 1.74 mas/yr
|Parallax (π)||2.62 ± 0.51 mas|
|Distance||approx. 1,200 ly |
(approx. 380 pc)
|Absolute magnitude (MV)||−5.50|
|Surface gravity (log g)||3.5 cgs|
|Rotational velocity (v sin i)||220 km/s|
It bore the traditional name Menkib, Menchib, Menkhib or Al Mankib, from Mankib al Thurayya (Arabic for "shoulder" [of the Pleiades]). In 2016, the International Astronomical Union (IAU) organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name Menkib for this star on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.
In Chinese, 卷舌 (Juǎn Shé), meaning Rolled Tongue, refers to an asterism consisting of Xi Persei, Nu Persei, Epsilon Persei, Zeta Persei, Omicron Persei and 40 Persei. Consequently, the Chinese name for Xi Persei itself is 卷舌三 (Juǎn Shé sān, "the Third Star of Rolled Tongue").
Xi Persei has an apparent magnitude of +4.06 and is classified as a blue giant (spectral class O7.5III). It is intrinsically 12,700 times brighter than the Sun with absolute magnitude −5.5 in the V band. If the ultraviolet light and light from other wavelengths that emanates from Menkib is included, its total bolometric luminosity is 263,000 times that of the Sun.
The star has a mass of some 30 solar masses and a surface temperature of 35,000 kelvins, making it one of the hottest stars that can be seen with the naked eye. The fluorescence of the California Nebula (NGC 1499) is due to this star's prodigious radiation. It is a member of the Perseus OB2 association of co-moving stars, but may be a runaway star since it is now separated by 200 pc from the association's center and has an unusually high radial velocity.