Scientists tease out mysteries of the Milky Way\'s most massive stars

Deep within some of the darkest, coldest and densest clouds in our galaxy lies the answer to why some stars grow so massive, U.S. astronomers say. Using a radio telescope in Chile, scientists have been looking into objects known as infrared dark clouds to search for telltale signs of star formation. Their search is for massive stars -- those at least eight times the mass of our sun -- larger than the majority of stars in the Milky Way galaxy. In these massive and dense clouds, they said, gravity should have already overwhelmed their supporting gas pressure, collapsing them to form new, sun-mass stars. An absence of stars would be a hint something extra was supporting the cloud, astrophysicist Jonathan Tan of the University of Florida, Gainesville, said. "A starless core would indicate that some force was balancing out the pull of gravity, regulating star formation, and allowing vast amounts of material to accumulate in a scaled-up version of the way our own sun formed," Tan, lead author of a paper published in the Astrophysical Journal, said. Some astrophysicists had believed two separate models of star formation are needed: one for sun-like stars and one for these massive stars." Not so, said Tan; the giant clouds studied are quite similar to the nurseries of sun-like stars, but simply scaled-up by tens or a hundred times. "This [study] suggests that massive stars and sun-like stars follow a universal mechanism for star formation," he said. "The only difference is the size of their parent clouds."