Spewing superdust.

Astronomers have identified a type of supernova as the main source of space dust, one of the building blocks of stars and planets.

A core-collapse supernova--the most common type of exploding star--is triggered when a massive star can no longer resist the power of its own gravity. The star's core implodes while its outer layers blast into space. The material that's expelled in this way eventually condenses, and new observations suggest that most cosmic dust comes from this condensation.

Angela Speck of the University of Missouri-Columbia and her colleagues used data from visible-light telescopes as well as NASA's infrared Spitzer Space Telescope to study the supernova 2003gd, about 30 million light-years from Earth. Mid-infrared observations of the supernova 499 to 678 days after it appeared indicate that there were large amounts of dust coming from the explosion. Theory suggests that the dust from the supernova may be as heavy as 2 percent of the mass of the sun, Speck and her colleagues report in an upcoming Science.

If that rate of dust expulsion is typical, it would suggest that core-collapse supernovas have been major producers of dust throughout cosmic history.--R.C.