Xi Persei

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Menkib, ξ Per
Perseus constellation map.svg
Cercle rouge 100%.svg

Stars of Perseus
Observation data
Epoch J2000      Equinox J2000
Constellation Perseus
Right ascension 03h 58m 57.90229s
Declination +35° 47′ 27.7132″
Apparent magnitude (V) 4.06
Spectral type O7.5III(n)((f))[1]
U−B color index -0.89
B−V color index +0.02
Variable type slightly variable
Radial velocity (Rv) 70.1 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[1]
Mass 26[1]-36[2] M
Radius 14[2] R
Luminosity 263,000[1] L
Surface gravity (log g) 3.5[1] cgs
Temperature 35,000[2] K
Rotation 220[1]
Age 2–3×106 years
Other designations
46 Per, HR 1228, HD 24912, FK5 148, SAO 56856
Database references

Xi Persei (ξ Per) is a star in the constellation Perseus. It has the traditional name Menkib (Menchib, Menkhib, Al Mankib from Mankib al Thurayya (Arabic for "shoulder" [of the Pleiades]). Menkib has an apparent magnitude of +4.06 and is classified as a blue giant (spectral class O7.5III). It is approximately 1800 light years from Earth.

It is intrinsically 12,700 times brighter than the Sun with absolute magnitude -5.5 in the V band. If the ultraviolet light that emanates from Menkib is included in 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.


  1. ^ a b c d e f Repolust, T.; Puls, J.; Herrero, A. (2004). "Stellar and wind parameters of Galactic O-stars. The influence of line-blocking/blanketing". Astronomy and Astrophysics 415 (1): 349–376. Bibcode:2004A&A...415..349R. doi:10.1051/0004-6361:20034594.  edit
  2. ^ a b c Krticka, J.; Kubat, J. (2010). "Comoving frame models of hot star winds. I. Test of the Sobolev approximation in the case of pure line transitions". Astronomy and Astrophysics 519: A50. arXiv:1005.0258. Bibcode:2010A&A...519A..50K. doi:10.1051/0004-6361/201014111. 

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