Kakkab (Alpha Lupi)

Alpha Lupi

Image credit: ESO Online Digitized Sky Survey.

Kakkab (Alpha Lupi) is the brightest star in the constellation Lupus; its (rarely used) ancient name comes from the phrase Kakkab Su-gub Gud-Elim meaning "the Star Left of the Horned Bull."


Kakkab is a hot giant B star belonging to the Upper Centaurus-Lupus Association (UCL), which in turn is part of a huge collection of O and B stars called the Scorpius-Centaurus Association. From analysis of all its members, UCL lies at an average distance of 450 light-years, which fits well with Kakkab's individually measured distance.


Like many of its spectral type, Kakkab is a Beta Cephei star, a variable that pulsates subtly with multiple periods. With a major oscillation cycle of 0.259847 days (the period really is known to such accuracy), in which it varies by only 0.03 magnitudes (about 3%), Kakkab has one of the longest periods of its class. A secondary pulsation takes 0.236798 days. A 13th magnitude star, just 28" away, may be a genuine companion of Kakkab or may be simply an optical double.


visual magnitude 2.30
absolute magnitude -3.83
spectral type B1.5III
luminosity 18,000 Lsun
temperature 21,600 K
mass 10 to 11 Msun
distance 548 light-years (168 pc)
position RA 14h 41m 55.8s,
Dec -47° 23' 18"