Dusty Stars

StarDate: January 21, 2009

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Like a pair of tacks holding up the descending curtain of twilight, two bright stars make a brief appearance in the western sky as night falls. Brilliant Vega is quite low in the northwest, while slightly fainter Fomalhaut is the same height in the southwest. They set a couple of hours after the Sun.

Both stars are hotter, brighter, and more massive than the Sun. They're a lot younger, too. And they have one other thing in common: they're encircled by disks of dust that may contain planets.

Here on Earth, dust is a pest. But beyond Earth, it's a great help in the search for young planetary systems. As it's warmed by the stars, the dust produces a lot of infrared energy, which can be detected by telescopes in space.

Dust grains are embedded in the clouds that give birth to stars. Some of the dust is incorporated into the star itself, but a lot remains outside the star. These solid particles can stick together to form larger and larger lumps. If there's enough dust, then the lumps may grow big enough to make planets. In fact, that's what happened in our own solar system four and a half billion years ago.

Disks of dust encircle quite a few other stars. Some of the stars also have confirmed planets. Fomalhaut may have at least one planet. There's no evidence of any planets around Vega, but the search continues.

The dust around these stars may contain some of the building blocks of life, and we'll talk about that tomorrow.

Script by Damond Benningfield, Copyright 2008

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