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Crimson Star

February 3, 2013

One of the reddest stars in the galaxy bounds across the south on February evenings, hidden in the “fur” of Lepus, the hare. Its primary name is R Leporis, but it’s better known as Hind’s Crimson Star for the astronomer who discovered it in the 19th century.

The star looks so red for a couple of reasons, both of which are related to its age.

Hind’s Crimson Star is in the final stages of life, so its outer layers have puffed up to giant proportions — about 75 times the Sun’s diameter. That’s caused its outer layers to get cooler, so they shine reddish orange.

At the same time, a lot of carbon has been dredged from the star’s interior and pulled to the surface. The carbon absorbs blue light, which enhances the star’s red color.

Some of the carbon, along with other elements, is being blown into space by a strong “wind” from the surface of the star. This wind is much thicker than the wind from the surface of the Sun. And it’s a first step in the star’s demise. Eventually, the star’s outer layers will all blow out into space, forming a glowing bubble. Over tens of thousands of years, the bubble will spread out and vanish from sight. After that, only the star’s hot core will remain — a tiny stellar corpse known as a white dwarf.

Lepus is in the south as night falls, below the feet of Orion. Hind’s Crimson Star is too faint to see with the eye alone. But a small telescope reveals its rich red color — the color of a dying star.


Script by Damond Benningfield, Copyright 2012

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