Mighty Hercules stands high in the east as night falls at this time of year. His most prominent feature is the Keystone, a lopsided square of modest stars that represents the strongman’s body. But the constellation’s brightest star isn’t part of the Keystone. Instead, it represents the entire strongman: Its name, Kornephoros, comes from a Greek word that means “the club bearer” — Hercules himself.
Like most of the stars in the galaxy, there’s more to Kornephoros than meets the eye: It consists of two stars, not one. One star is smaller and fainter than the Sun, so it’s not visible to the eye alone.
The visible star, on the other hand, is about three times the mass of the Sun, almost 20 times the Sun’s diameter, and 150 times its brightness. So the star is an easy target even though it’s about 140 light-years away.
The star is nearing the end of its life. It’s probably consumed the hydrogen fuel in its core, converting it to helium. That’s caused the core to get smaller and hotter. The extra energy pushes on the star’s outer layers, causing them to puff up to giant proportions.
Today, Kornephoros is fusing the helium to make carbon and oxygen. Eventually, though, that process will end. The star will lose its outer layers, leaving only its dead core — and the “club bearer” will vanish from sight.
For now, though, look for it due east as night falls, halfway up the sky — the first modestly bright star to the right of the Keystone.
Script by Damond Benningfield