More Moon and Antares

StarDate: September 24, 2009

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The two stars that make up the Antares system are both big, bright, and heavy. But one of them is twice as heavy as the other, which means they'll end their lives quite differently.

Antares is to the right or lower right of the Moon at nightfall this evening. It shines with a beautiful orange color.

That ruddy glow comes from the heavier of the two stars, known as Antares A. It's about 15 times more massive than the Sun. It's also far larger than the Sun. In fact, you could fit more than 30 million Suns inside Antares A.

Because of the star's great mass, Antares A's total lifespan will be in the millions of years, versus billions of years for the Sun.

When it can no longer produce nuclear energy in its core, Antares A will explode as a supernova, blasting its outer layers into space at a few percent of the speed of light. Its core will be crushed to form an ultradense neutron star. It'll be several times as massive as the Sun, but no bigger than a city.

Its companion star, Antares B, is only about half as massive. That means it'll live millions of years longer.

When it can no longer produce nuclear energy, it will also shed its outer layers -- but much more gently. Its core most likely will become a white dwarf. It'll be a little more massive than the Sun, but as big as Earth, so it won't be nearly as dense as a neutron star.

So Antares A and B are both destined to get a lot smaller -- they'll just do it in very different ways.

Script by Damond Benningfield, Copyright 2009

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