Supersizing Stars

Enormous suns have baffled astronomers for years. On the one hand, young stars eventually produce so much radiation that they ought to repel any surrounding building material, and computer models suggested this should limit their mass to about 10 times that of the sun. On the other hand, direct observations routinely turn up bodies more than twice that size. What phenomenon could be creating such stellar giants?
A team using the Very Large Array radio telescope in Socorro, New Mexico, thinks it has the answer. The group studied G24 A1, a young star of about 20 solar masses located approximately 25,000 light-years away in a star-forming region. The researchers traced the motions of gas around the star by studying the Doppler shift of radio waves emitted by ammonia molecules. They found molecules blasting away from the star, pushed by the waves of outgoing radiation. But they also spotted gas falling back toward the star and continuing to feed its bulk. And they discovered ammonia orbiting the star, suggesting the presence of a doughnut-shaped disk of gas and dust wrapped around the stellar body.