You are here


January 14, 2011

If you could catch the hot gas that the star Alnilam is blowing into space, in a million years you'd have enough to make two stars as heavy as the Sun. But you wouldn't be able to tell any difference in Alnilam itself because it's one of the monsters of the Milky Way.

Alnilam is the center star in Orion's Belt, a compact line of three bright stars that points up from the eastern horizon on January evenings.

Alnilam is the most impressive member of the belt. It's the brightest of the three stars, even though it's hundreds of light-years farther than the other two. And while each of the others actually consists of two stars, Alnilam moves through the galaxy alone.

Alnilam is a supergiant. It's about 40 times as massive as the Sun, tens of thousands of degrees hotter, and hundreds of thousands of times brighter. Its radiation is so intense, in fact, that it pushes a dense "wind" of charged particles from the surface of Alnilam out into space at millions of miles an hour.

Although Alnilam is only a few million years old, it's rapidly nearing the end of its life. It's consuming its original hydrogen fuel, and over the next few million years, it'll "burn" through a series of heavier elements forged in its core. Eventually, it won't be able to sustain that process any longer. Its core will collapse, while its outer layers will blast into space as a supernova -- briefly outshining most of the other stars in the galaxy combined.

Script by Damond Benningfield, Copyright 2010

Get Premium Audio

Listen to today's episode of StarDate on the web the same day it airs in high-quality streaming audio without any extra ads or announcements. Choose a $8 one-month pass, or listen every day for a year for just $30.