Previous observations had indicated that winds emanating from red giant stars near the end of their lives create cosmic dust, tiny solid particles mainly made up of carbon and silicates. But because it takes about nine billion years for stars such as our sun to reach this stage, it remained unclear what supplied cosmic dust in the first billion years of the universe. Although scientists had found traces of ancient particles around supernovae, they needed more evidence to establish the link. "The origin of cosmic dust is, in fact, the basic question of the origin of our planet and others," lead author Loretta Dunne of Cardiff University says. "Effectively, we live on a very large collection of cosmic dust grains and yet, until now, we have not been sure where cosmic dust is made."
Dunne and her colleagues used SCUBA, a powerful camera attached to the James Clerk Maxwell Telescope in Hawaii, to investigate Cassiopeia A, the remnant of a supernova explosion located 11,000 light-years from Earth. Whereas earlier attempts had only located relatively warm dust particles, SCUBA detected frigid dust particles at temperatures as low as -257 degrees Celsius. In all, the astronomers discovered dust totaling between two and four times the mass of the sun and "over 1,000 times what's been seen before," according to team member Stephen Eales of Cardiff University. "Cassiopeia A must have been extremely efficient at creating dust from the elements available."