‘Sailing’ Stars

Much of what we see in the night sky is an illusion. Some of the brighter stars aren’t really all that bright. They look impressive only because they’re close by. There’s one group of stars, though, where what you see is what you get.

Four stars in the constellation Corvus, the crow, form a small lopsided box that resembles a sail. It’s in the south as night falls. The star at the top left corner of the sail is known as Delta Corvi. Clockwise from there, the other stars are Gamma, Epsilon, and Beta Corvi.

To the eye alone, the most impressive member of the quartet is Gamma Corvi. And in this case, appearances aren’t deceiving. It’s the brightest, hottest, and most massive of the four.

The star is also known as Gienah, from an Arabic phrase that means “the wing of the crow.” It’s actually a system of two stars. One of them is small and unimpressive. But the other is quite impressive. It’s more than four times the mass of the Sun, about 330 times brighter, and thousands of degrees hotter.

And even though it’s only a few percent of the Sun’s age, Gamma Corvi’s bright star is nearing the end of its life. Because of its mass, it’s used up the original hydrogen in its core, which fueled its nuclear reactions. Now it’s going through some changes. Among other things, its outer layers have swollen to giant proportions. That makes the star easy to see, even though it’s more than 150 light-years away — the bright wing of the crow.

Script by Damond Benningfield