Magnitude 2.68 Apparent magnitude (V) 2.68 | Constellation Lupus | |
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Beta Lupi (β Lupi, β Lup), or Kekouan, is a star in the southern constellation of Lupus. It has an apparent visual magnitude of 2.7, 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.
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Properties
The stellar classification of B2 III indicates this is a giant star. The effective temperature of the star's outer envelope is 24,090 K, giving it the blue-white hue of a B-type star. With an age of around 25 million years, 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 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.
This is a multi-period Beta Cephei variable with a dominant oscillation period of 0.232 days. 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. Beta Lupi has a high proper motion of more than 50 mas per year, suggesting a significant transverse velocity.
It lies close to the supernova remnant SN 1006.
Name
In Chinese, 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. Consequently, β Lupi itself is known as 騎官四 (Qí Guān sì, English: the Fourth Star of Imperial Guards.). From the French rendering of this Chinese name derives the traditional European name Kekouan (Ke Kwan).