Astronomers have long known that we're all made of stardust. Now they've gotten an enlightening glimpse into one of the explosive events that loads the universe with the dusty seeds of life.
Researchers re-examined the remnant of an exploded star and found a thousand times more smoke-like dust particles than had been detected before. The finding helps explain why galaxies are dust-laden almost to the beginning of time, astronomers said.
The young universe was no place for life. It was mostly hydrogen and helium. Heavier stuff -- dust, metals and all the other ingredients needed to make planets, plants and people -- was forged in stars and, especially, in the catastrophic explosions of the most massive stars.
These supernovae, as they're called, cast material into space that then goes into the birth of subsequent generations of stars, which in turn create ever-heavier elements. Astronomers long presumed that planets could only form around later-generation stars, where lots of leftover dust and rock would orbit each newborn star.
Dust factory
The new discovery of dust, in a supernova remnant called Cassiopeia A, shows that stellar explosions in general may make more dust than expected. Researchers speculate that similar explosions in the young universe made the dust that has been found in some of the earliest galaxies.
Dust around supernovae is hard to detect. In addition to most supernovae being very, very far away, the dust is cold and does not emit or reflect much light that can be seen.
The new study, detailed earlier this month in the journal Nature, used the SCUBA submillimeter-wavelength camera on the James Clerk Maxwell Telescope in Hawaii.
SCUBA detected a dust shell in Cassiopeia A that contains up to four times the mass of the Sun.
"This is over a thousand times what's been seen before," said study team member Steve Eales of Cardiff University in the UK. "Cassiopeia A must have been extremely efficient at creating dust from the elements available."
Cassiopeia A offers a rare chance to study supernovae within our Milky Way Galaxy.
Its star, probably 30 times more massive than the Sun, collapsed about 300 years ago after using up its primary fuel. A black hole was formed out of some of the remaining mass, theory holds, and the rest was ejected in the explosion. The material is still zooming outward at 22 million mph (10,000 kilometers per second).
More dusty evidence
In recent years, observations by SCUBA and other telescopes have revealed surprising amounts of dust in galaxies more than 10 billion light-years away, the researchers said. Such galaxies are observed as they existed 10 billion years ago, when the universe was quite young. (The Big Bang, which presumably initiated the universe as we know it, occurred 13.7 billion years ago.)
Earlier this month, the universe's
was found in an environment of ancient stars. It is estimated to be 12.7 billion years old. Astronomers were stunned that there would have been enough dust and other heavy elements back then to create a planet."Dust has been swept under the cosmic carpet -- for years astronomers have treated it as a nuisance because of the way it hides the light from the stars," said Cardiff's Loretta Dunne, who led the new research.
"But then we found that there is dust right at the edge of the universe in the earliest stars and galaxies, and we realized that we were ignorant of even its basic origin," Dunne said. "Now, with these supernova dust factories, we can explain how that dust was made."
advertisement
