One of the reddest stars in the sky passes high overhead tonight. It's just south of the curve of the handle of the Big Dipper.
To casual stargazers, all stars look white. But if you look closely -- and especially if you look with binoculars -- you'll see many colors in the stars. For the most part, the colors are subtle.
But the color of the carbon star Y Canum Venaticorum is anything but subtle -- it's deep red. The star owes its color to two things. First, it's a cool star, and cool stars are redder than hot ones.
However, there's more to this star's color than just its low temperature. Y Canum Venaticorum is a carbon star. That means its atmosphere contains lots of carbon compounds. These compounds block much of the star's green, blue, and violet light, deepening its red hue.
Y Canum Venaticorum is in the constellation Canes Venatici, the hunting dogs. It's a faint constellation, but it's fairly easy to find because it's just south of the Big Dipper's handle. A good star map will help you find both the constellation and the star.
Y Canum Venaticorum is aging, and its light varies. When brightest, the star is visible to the unaided eye; when dimmest, you need a pair of binoculars to see it. Actually, no matter what its brightness, binoculars are a great way to observe Y Canum Venaticorum. They help bring out the color of this star -- one of the reddest in the entire sky.
Script by Ken Croswell, Copyright 2008
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