A star is a pretty good housekeeper. Over time, it either swallows or sweeps away most of the dust that surrounded it when it was born. But it has to keep working, because the planets and other bodies around it create more dust to mess things up again.
An example is a star system in the Pleiades, one of the most famous objects in the night sky. It's a cluster of hundreds of stars that forms a tiny dipper. It's high overhead at nightfall, and drops down the western sky later on.
The star system is known as HD 23514. Telescopes in space and on the ground have detected a bright infrared glow around the star -- the heat of a thick cloud of dust.
The amount of dust is probably similar to the amount found in our own solar system right after its birth. Much of the dust coalesced to form planets, while most of the rest either fell into the Sun or was blown away by the Sun's radiation.
HD 23514 is around 100 million years old. By that age, it should already have disposed of most of its dust.
But astronomers from the Gemini Observatory suggested that the system gets an occasional "dusting" when big chunks of rock slam together and blast each other to bits. The chunks could be hundreds of miles across, and may be left over from the process that gave birth to planets.
So if planets orbit the star, they may still take an occasional beating from smaller objects -- a beating that scatters a lot of dust for the star to clean up.
Script by Damond Benningfield, Copyright 2008
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