What a Star’s Orbiting Disk Is Made Of

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Source:  Dennis Overbye, Solar System Formation

Excerpt: …Back in 2002, astronomers from Wesleyan University concluded that a star brightening and waning in an unusual 48-day rhythm was dipping in and out of stuff swirling around the star in a so-called protoplanetary disk. …Now, after six more years of observation with an international group of astronomers, led by William Herbst of Wesleyan, researchers say they know what the stuff in this disk is. …sand-size grains, roughly a millimeter in diameter, which must have grown from infinitesimal dust particles over the three million years that the star… “This is the first step in going from smoke particles to macroscopic things like planets and asteroids,” Dr. Herbst said….

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