Astronomers probe secrets of giant star cluster in the making

U.S. astronomers say they've penetrated a cosmic fog of dust to peer into one of the best-kept secrets in our galaxy, an active stellar nursery. The star-forming region known as W49A shines 100 times brighter than the Orion nebula, but is so obscured by dust that very little visible or infrared light escapes, researchers at the Harvard-Smithsonian Center for Astrophysics said. The Smithsonian's Submillimeter Array has allowed them to peer through the dusty fog to provide the first clear view of this stellar nursery, revealing an active site of star formation being fed by streamers of inward falling gas, a center release said Monday. W49A, located about 36,000 light-years from Earth on the opposite side of the Milky Way, is an example of the sort of vigorous star formation seen in so-called "starburst" galaxies, where stars form 100 times faster than in our galaxy. "We were amazed by all the features we saw in the SMA images," study lead author Roberto Galvan-Madrid said. About 100,000 stars exist within a space only 10 light-years on a side, the researchers said; in contrast, fewer than 10 stars lie within 10 light-years of our sun. Most star clusters in the galactic disk dissolve rapidly, their stars migrating away from each other under the influence of gravitational tides; it's why none of the sun's sibling stars remain nearby. However, W49A is compact and very dense, suggesting it might remain intact for billions of years, the researchers said.