Hubble Watches Dusty Disks Grow Up

The Hubble Space Telescope has compiled its first baby album of other worlds outside our solar system by capturing views of many young stars swaddled in dusty disks, astronomers announced at a press conference today at NASA Headquarters in Washington, D.C. Taken together, the photos span a range of cosmic processes that "spin stardust into planets," says astronomer Karl Stapelfeldt of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.

Shown here are infrared images of six of the youngest disks, girdling stars in a dark cloud 450 light-years away in the constellation Taurus. Each disk contains enough dust to produce thousands of Earth-sized planets, says astronomer Deborah Padgett of JPL and the California Institute of Technology. Perhaps less than 1 million years old, these disks--up to 15 times wider than our own solar system--are in a stage in which raw material is still cascading into the disks, Padgett says.

Another set of Hubble images shows older disks that have flattened into strikingly thin planes of debris around their stars. These include one that Stapelfeldt's team has dubbed the "Hamburger star"--a narrow dust patty slicing across bright buns of light. "These disks probably have 100 times less material than the younger ones," Stapelfeldt says, noting that some dust already may have coalesced into planets.

Images of more mature stars girdled by striking "rings" of dust, released by astronomers in January, depict systems in which large planets almost certainly have formed and cleared out much of the dust, says astronomer Glenn Schneider of the University of Arizona in Tucson.

"These images allow us for the first time to paint a big picture, an evolutionary sequence of how solar systems and planets like those in our solar system came to be," says Hubble project scientist David Leckrone of NASA's Goddard Space Flight Center in Greenbelt, Maryland. But Steven Beckwith, director of the Space Telescope Science Institute in Baltimore, Maryland, cautions that the images have not yet been linked to planet formation. "We haven't actually seen planets within these disks," he says. Spotting candidate planets would complete the evolutionary chain from dust to new worlds, he notes.