Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Lupus |
Right ascension | 14h 41m 55.75579s [1] |
Declination | –47° 23′ 17.5155″ [1] |
Apparent magnitude (V) | 2.30 [2] (2.29 - 2.34 [3]) |
Characteristics | |
Spectral type | B1.5 III [4] |
U−B color index | –0.88 [2] |
B−V color index | –0.20 [2] |
Variable type | β Cep [3] |
Astrometry | |
Radial velocity (Rv) | +5.4 ± 0.6 [5] km/s |
Proper motion (μ) |
RA: −20.94
[1]
mas/
yr Dec.: −23.67 [1] mas/ yr |
Parallax (π) | 7.02 ± 0.17 mas [1] |
Distance | 460 ± 10
ly (142 ± 3 pc) |
Absolute magnitude (MV) | −4.3 [6] |
Details | |
Mass | 10.1 ± 1.0 [7] M☉ |
Luminosity | 25,000 [6] L☉ |
Surface gravity (log g) | 3.46 [6] cgs |
Temperature | 21,820 ± 2,160 [8] K |
Metallicity [Fe/H] | 0.04 [9] dex |
Rotational velocity (v sin i) | 16 [5] km/s |
Age | 16–20 [5] Myr |
Other designations | |
Database references | |
SIMBAD | data |
Alpha Lupi (α Lupi, α Lup) is a blue giant star, and the brightest star in the southern constellation of Lupus. According to the Bortle Dark-Sky Scale, its apparent visual magnitude of 2.3 [2] makes it readily visible to the naked eye even from highly light-polluted locales. Based upon parallax measurements made during the Hipparcos mission, [11] the star is around 460 light-years (140 parsecs) from the solar system. [1] It is one of the nearest supernova candidates. [12]
Alpha Lupi is a giant star with a stellar classification of B1.5 III. [4] It has about ten times the mass of the sun (~10 M☉) [7] yet is radiating 25,000 times the Sun's luminosity. [6] The outer atmosphere has an effective temperature of 21,820 K, [8] which gives it the blue-white glow of a B-type star. In 1956 it was identified as a Beta Cephei variable by Bernard Pagel and colleagues, [14] which means it undergoes periodic changes in luminosity because of pulsations in the atmosphere. The variability period is 0.29585 days, [9] or just over 7 hours, 6 minutes. The magnitude varies by about 0.05 magnitudes, or about 5% of its brightness. A 14th magnitude star situated 26" from Alpha Lupi is listed as a companion in double star catalogues. [15]
This star 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] This is a gravitationally unbound stellar association with an estimated age of 16–20 million years. The association is also the source of a bubble of hot gas that contains the Sun, known as the Local Bubble. [5]
Visible from the Southern Hemisphere for much of the year, it can also be viewed for a shorter season from the northern tropics and from parts of the northern subtropical latitudes.
α Lupi ( Latinised to Alpha Lupi) is the star's Bayer designation.
In Chinese, Kekouan 騎官 (Qí Guān), meaning Imperial Guards, refers to an asterism consisting of α Lupi, γ Lupi, δ Lupi, κ Centauri, β Lupi, λ Lupi, ε Lupi, μ Lup, π Lupi, and ο Lupi. [16] Consequently, the Chinese name for α Lupi itself is 騎官十 (Qí Guān shí, English: the Tenth Star of Imperial Guards.). [17]
R. H. Allen described this star as having the Chinese name Yang Mun or Men(南門), meaning "the South Gate", in his work Star-Names and their Meanings. [18] In Chinese astronomy, 南門 is located in Horn mansion and consisted of α and ε Centauri. It was referred to as Yang Mun, meaning "the south Gate". Allen also suggested that the Babylonian name for the star was "Kakkab Su-gub Gud-Elim" (Star Left Hand of the Horned Bull). [18]