| |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Lupus |
| Right ascension | 14h58m 31.92536s[1] |
| Declination | −43° 08′ 02.2699″[1] |
| Apparent magnitude (V) | 2.68[2] |
| Characteristics | |
| Spectral type | B2 III[3] |
| U−B color index | −0.902[4] |
| B−V color index | −0.226[4] |
| Variable type | β Cep[5] |
| Astrometry | |
| Radial velocity (Rv) | +0.1 ± 1.0[3] km/s |
| Proper motion (μ) | RA: −35.78[1] mas/yr Dec.: −39.83[1] mas/yr |
| Parallax (π) | 8.52 ± 0.18 mas[1] |
| Distance | 383 ± 8 ly (117 ± 2 pc) |
| Absolute magnitude (MV) | −3.3[6] |
| Details | |
| Mass | 8.8±0.2[7] M☉ |
| Radius | 6.6[8] R☉ |
| Luminosity | 10,000[6] L☉ |
| Surface gravity (log g) | 3.76[6] cgs |
| Temperature | 24,090[9] K |
| Metallicity [Fe/H] | −0.35±0.11[5] dex |
| Rotational velocity (v sin i) | 92[3] km/s |
| Age | 24.6±2.7[7] Myr |
| Other designations | |
Kekouan, β Lup, CD−42° 9853, FK5 552, HD 132058, HIP 73273, HR 5571, SAO 225335[10] | |
| Database references | |
| SIMBAD | data |
Beta Lupi (Latinized from β Lupi) or Kekouan (/ˈkɛkwɑːn/), is a star in the southern constellationofLupus. It has an apparent visual magnitude of 2.7,[2] making it readily visible to the naked eye. Based upon parallax measurements, this star is located at a distance of about 383 light-years (117 parsecs) from Earth.[2]
The stellar classification of B2 III indicates this is a giant star.[3] The effective temperature of the star's outer envelope is 24,090 K,[9] giving it the blue-white hue of a B-type star.[11] With an age of around 25 million years,[7] it is near the end of its hydrogen phase, where hydrogen is fused into the element helium, and transferring into a red supergiant star. At about 8.8[7] solar masses, it may have enough mass to end its life as a Type II supernova, but there is the possibility of Beta Lupi becoming a white dwarf.[12]
This is a multi-period Beta Cephei variable with a dominant oscillation period of 0.232 days.[5] It is a proper motion member of the Upper Centaurus–Lupus sub-group in the Scorpius–Centaurus OB association, the nearest such co-moving association of massive stars to the Sun.[6] Beta Lupi has a high proper motion of more than 50 mas per year, suggesting a significant transverse velocity.[13]
It is positioned about 1.3° SSW of the supernova remnant SN 1006.[14]
InChinese, 騎官 (Qí Guān), meaning Imperial Guards, refers to an asterism consisting of β Lupi, γ Lupi, δ Lupi, κ Centauri, λ Lupi, ε Lupi, μ Lup, π Lupi, ο Lupi and α Lupi.[15] Consequently, the Chinese name for β Lupi itself is 騎官四 (Qí Guān sì, English: the Fourth Star of Imperial Guards.).[16] From the French rendering of this Chinese name derives the traditional European name Kekouan (Ke Kwan).[17]
