Many of the stars that sparkle across the night sky are deceptive — there’s much more to them than the eye can see. That’s because most of those points of light are the combined glow of two stars or more.

A famous example is Regulus, the bright heart of the lion. It stands close to the lower right of the Moon at nightfall, and below the Moon as they set, around dawn.

What we see as Regulus is a star that’s bigger and hotter than the Sun, and hundreds of times brighter. It has at least three companions. They’re all so faint, though, that they add little or nothing to the light we see from the system’s main star.

One of the companions is a white dwarf — the dead core of a star that once was more impressive than the visible star. It’s so close to the main star that it’s impossible to see through the glare.

The two other known stars also form a pair. They’re hundreds of billions of miles away from the bright pair. And they’re much fainter, so they’re visible only through a telescope.

The brighter member of this pair is a bit smaller, cooler, and fainter than the Sun. And its companion is cooler and fainter still — a bare cosmic ember that’s only a small fraction of the Sun’s brightness. The two stars are separated by about a hundred times the distance between Earth and the Sun. At that range, it takes them centuries to complete a single orbit around each other — under the glow of the star we know as Regulus.
 

Script by Damond Benningfield

Support McDonald Observatory