Astronomers have at last found definitive evidence that the universe's first dust - the celestial stuff that seeded future generations of stars and planets - was forged in the explosions of massive stars. The findings, made with NASA's Spitzer Space Telescope, are the most significant clue yet in the longstanding mystery of where the dust in our very young universe came from.
Scientists had suspected that exploding stars, or supernovae, were the primary source, but nobody had been able to demonstrate that they can create copious amounts of dust - until now. Spitzer's sensitive infrared detectors have found 10,000 Earth masses worth of dust in the blown-out remains of the well-known supernova remnant Cassiopeia A.
"Now we can say unambiguously that dust - and lots of it - was formed in the ejecta of the Cassiopeia A explosion. This finding was possible because Cassiopeia A is in our own galaxy, where it is close enough to study in detail," said Jeonghee Rho of NASA's Spitzer Science Center at the California Institute of Technology in Pasadena. Rho is the lead author of a new report about the discovery appearing in the Jan. 20 issue of the Astrophysical Journal.
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| ©NASA/JPL-Caltech
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| This beautiful bulb might look like a Christmas ornament but it is the blown-out remains of a stellar explosion, or supernova. The remains, called Cassiopeia A, are shown here in an infrared composite from NASA's Spitzer Space Telescope. Silicon gas is blue and argon gas is green, while red represents about 10,000 Earth masses worth of dust. Yellow shows areas where red and green overlap. The fact that the red and green do overlap indicates that this supernova is synthesizing dust and gas together. This is the smoking gun indicating that supernovae were significant suppliers of fresh dust in the very early universe -- something that was hard to demonstrate prior to the Spitzer observations.
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