  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Perseus |
| Right ascension | 03h 58m 57.90229s[1] |
| Declination | +35° 47′ 27.7132″[1] |
| Apparent magnitude (V) | 4.04[2] |
| Characteristics | |
| Spectral type | O7.5III(n)((f))[3] |
| U−Bcolor index | −0.93[2] |
| B−Vcolor index | +0.02[2] |
| Variable type | slightly variable[4] |
| Astrometry | |
| Radial velocity (Rv) | 65.40[5] km/s |
| Proper motion (μ) | RA: 3.62[1]mas/yr Dec.: 1.74[1]mas/yr |
| Parallax (π) | 2.62±0.51 mas[1] |
| Distance | approx. 1,200 ly (approx. 380 pc) |
| Absolute magnitude (MV) | −5.50[3] |
| Details | |
| Mass | 26[3]-36[6] M☉ |
| Radius | 14[6] R☉ |
| Luminosity | 263,000[3] L☉ |
| Surface gravity (log g) | 3.5[3] cgs |
| Temperature | 35,000[6] K |
| Rotational velocity (v sin i) | 220[3] km/s |
| Age | ~7[7] Myr |
| Other designations | |
| 46 Per,HR 1228,HD 24912,FK5 148,SAO 56856,HIP 18614,BD+35°775 | |
| Database references | |
| SIMBAD | data |
Xi Persei (ξ Persei, abbreviatedXi Per,ξ Per), known also asMenkib/ˈmɛŋkɪb/,[8][9] is astar in theconstellation ofPerseus. Based uponparallax measurements taken during theHipparcos mission, it is approximately 1,200light-years from theSun.
ξ Persei (Latinised toXi Persei) is the star'sBayer designation.
It bore the traditional nameMenkib,Menchib,Menkhib orAl Mankib, fromMankib al Thurayya (Arabic for "shoulder" [of thePleiades]). In 2016, theInternational Astronomical Union (IAU) organized aWorking Group on Star Names (WGSN)[10] to catalogue and standardize proper names for stars. The WGSN approved the nameMenkib for this star on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.[9]
InChinese,卷舌 (Juǎn Shé), meaningRolled Tongue, refers to anasterism consisting of Xi Persei,Nu Persei,Epsilon Persei,Zeta Persei,Omicron Persei and40 Persei.[11] Consequently, theChinese name for Xi Persei itself is卷舌三 (Juǎn Shé sān, "the Third Star of Rolled Tongue").[12]
Xi Persei has anapparent magnitude of +4.06 and is classified as ablue giant (spectral class O7.5III). It is intrinsically 12,700 times brighter than theSun withabsolute magnitude −5.5 in the V band. If the ultraviolet light and light from other wavelengths that emanates from Menkib is included, its totalbolometric luminosity is 263,000 times that of the Sun.
The star has a mass of some 30solar masses and a surface temperature of 35,000kelvins, making it one of the hottest stars that can be seen with the naked eye. The fluorescence of theCalifornia Nebula (NGC 1499) is due to this star's prodigious radiation.[7] It is a member of the Perseus OB2 association of co-moving stars, but may be arunaway star since it is now separated by 200 pc from the association's center and has an unusually highradial velocity.[13]
