At magnitude 2.77, Kornephoros is the brightest star in Hercules. The constellation that honors the Greek hero was originally known as "the Kneeler," a name of ancient though unknown significance. Kornephoros has the Bayer designation β Her; it lost the α designation to Rasalgethi, whose name means "the kneeler's head." Kornephoros, which from Greek means "club-bearer," refers to one of the mighty weapons of Hercules himself. Kornephoros has another proper name, Rutilicus, a corruption of a Latin word meaning "armpit".
Properties and Evolution
In reality, Kornephoros is a relatively cool (4900 K) class G7 III yellow giant, 148 light years away, with a luminosity of 175 suns, and a radius nearly 20 times solar. Its temperature and luminosity indicate that it contains about three solar masses. It is a significant X-ray source that reveals some magnetic activity, and it has an enhanced nitrogen abundance relative to carbon. Otherwise, it is a very normal star for its state of evolution.
β Her began life as a hot main-sequence class B star, fusing hydrogen into helium in its core. As a giant, the star is evolving rapidly, and is now fusing its core helium into carbon and oxygen. Kornephoros is not massive enough to explode as a supernova, and will eventually die as a fairly massive white dwarf.
Astrometric Companion
Like many other stars, Kornephoros also has a companion, but an unseen one. It is known only through the gravitational effect it has on the visible star, causing it to move back and forth across our line of sight. The companion, about which almost nothing is known, probably has a mass a bit higher than the Sun's.
[Adapted from STARS by Jim Kaler, Professor Emeritus of Astronomy, University of Illinois]