Alpha Lupi

Stellar classification



  • X 281
  • Y 89
  • Z 359
→ Sol: 465

Object type

  • Variable Star of beta Cep type
  • Star
  • Double or multiple star
  • Infra-Red source
  • UV-emission source
  • Variable Star
  • X-ray source
simbad:* alf Lup


Alpha Lupi (α Lupi, α Lup) is the brightest star in the southern constellation of Lupus. According to the Bortle Dark-Sky Scale, its apparent visual magnitude of 2.3 makes it readily visible to the naked eye even from highly light-polluted locales. Based upon parallax measurements made during the Hipparcos mission, the star is located at a distance of around 460 light-years (140 parsecs) from Earth. It is one of the nearest supernova explosion candidates.

Alpha Lupi is a giant star with a stellar classification of B1.5 III. It has about ten times the mass of the Sun but is radiating 25,000 times the Sun's luminosity. The outer atmosphere has an effective temperature of 21,820 K, 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, which means it undergoes periodic changes in luminosity because of pulsations in the atmosphere. The variability period is 0.29585 days, or just over 7 hours, 6 minutes. The magnitude varies by about 0.05, or about 5% of the total luminosity. A 14th magnitude star situated 26" from Alpha Lupi is listed as a companion in double star catalogues.

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. 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.

This article uses material from the Wikipedia article "Alpha Lupi", which is released under the Creative Commons Attribution-Share-Alike License 3.0.