AL MINLIAR AL ASAD (Kappa Leonis). The name comes from the famed 15th century Persian astronomer Ulugh Beg, and appropriately means "the Lion's Nose," though the name is never used. We defer instead to "Kappa Leonis." At first perhaps dismissible as a common fourth (4.46, nearly fifth) magnitude orange class K (K2) giant, Kappa Leo can celebrate its being Number 1 in Leo. Flamsteed's number 1 (1 Leo) that is, and not just that, but Leo's eastern-most Greek-lettered star. That of course hardly makes it physically interesting. What does is are its companions, one of which led to an odd error. But first, what of the star itself? At a distance of 201 light years (remarkably accurate to 2 l-y), and with a temperature of 4375 Kelvin (from which we can deduce the amount of red and infrared radiation), Kappa Leo shines with the light of 95 Suns, which leads to a radius of 17 times solar. With a slow, ponderous projected equatorial rotation speed of just 1.9 kilometers per second, the star may take as long as 400 days, 1.1 years, to make a full turn. The iron content is close to solar. Theory is ambiguous as to mass and state of evolution. The star seems to carry roughly two solar masses, but with considerable uncertainty, as stars with a wide range of masses under these giant conditions have similar temperatures and luminosities. It could also be getting brighter as a red giant with a dead helium core (and an age of about a billion years since it was born as a class A1 dwarf), dimming with a helium core fusing into carbon and oxygen, or brightening again with a dead C-O core, in which case the age is closer to 1.5 billion years.

Kappa Leo has two neighbors, magnitude 9.7 Kappa B, which lies just 2.4 seconds of arc away and seems to have shown some orbital motion, and mag 11.1 Kappa C, which stands at a current separation of 149 seconds and whose motion clearly shows it just to be in the line-of-sight. Kappa B and C seem to have been confused with each other, as Kappa B is listed as "variable" with its "maximum" at its actual brightness and its "minimum" at the brightness of Kappa C. Not variable at all, B's absolute visual brightness shows it to be very much a solar-type dwarf. At a minimum actual distance of 150 Astronomical Units, sunlike Kappa B must take at least 1000 years to make a full orbit. From Kappa A, B would shine with the light of up to 10 full Moons, while from Kappa B, Kappa A might hit 1000 of them.
Written by Jim Kaler 4/01/11. Return to STARS.