Prof Herbst has been studying the star KH15D, which is actually two stars orbiting around each other. KH15D is uniquely located with some fairly unique properties such that his team has been able to determine more about the star’s makeup and formation.
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. At the time one astronomer called the system “a Rosetta stone,” for understanding how planets form.
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. In a paper published on Thursday in the journal Nature, they report that it is made of sand-size grains, roughly a millimeter in diameter, which must have grown from infinitesimal dust particles over the three million years that the star, known as KH 15D, has been in existence.
“This is the first step in going from smoke particles to macroscopic things like planets and asteroids,” Dr. Herbst said in an interview, noting that these grains were about the same size as those found in many meteorites. Observing starlight reflected from these grains, he said, represented a rare opportunity to study the structure and chemical properties of material in the inner parts of another planetary system.