NASA telescope finds evidence of first dust that helped in formation of early stars and planets

December 21st, 2007 - 2:01 pm ICT by admin  

Washington, Dec 21 (ANI): Astronomers, using NASA’s Spitzer Space Telescope, have found evidence of the universes first dust that helped in the formation of future generations of stars and planets.

The evidence has been found in the blown-out remains of the well-known supernova remnant Cassiopeia A, where 10,000 Earth masses worth of dust has been discovered.

Though scientists had suspected that exploding stars, or supernovae, were the primary source of the dust in our very young universe, nobody had been able to demonstrate that they can create copious amounts of dust, until now.

“Now we can say unambiguously that dust - and lots of it - was formed in the ejecta of the Cassiopeia A explosion, said Jeonghee Rho of NASA’s Spitzer Science Center at the California Institute of Technology in Pasadena. This finding was possible because Cassiopeia A is in our own galaxy, where it is close enough to study in detail,” he added.

Space dust is everywhere in the cosmos, in our own neck of the universe. But back when the universe was young, sun-like stars hadn’t been around long enough to die and leave dust.

That’s where supernovae come in. These violent explosions occur when the most massive stars in the universe die. Because massive stars don’t live very long, theorists reasoned that the very first exploding massive stars could be the suppliers of the unaccounted-for dust. These first stars, called Population III, are the only stars that formed without any dust.

For the new research, the astronomers analyzed the infrared light coming from Cassiopeia A using Spitzer’s infrared spectrograph, which spreads light apart to reveal the signatures of different elements and molecules.

“Because Spitzer is extremely sensitive to dust, we were able to make high-resolution maps of dust in the entire structure,” said Rho.

The map reveals the quantity, location and composition of the supernova remnant’s dust, which includes proto-silicates, silicon dioxide, iron oxide, pyroxene, carbon, aluminium oxide and other compounds. One of the first things the astronomers noticed was that the dust matches up perfectly with the gas, or ejecta, known to have been expelled in the explosion. This is the smoking gun indicating the dust was freshly made in the ejecta from the stellar blast.

“Dust forms a few to several hundred days after these energetic explosions, when the temperature of gas in the ejecta cools down,” said Takashi Kozasa, a co-author at the Hokkaido University in Japan.

Other objects in addition to supernovae might also contribute to the universe’s first dust.

Spitzer recently found evidence that highly energetic black holes, called quasars, could, together with supernovae, manufacture some dust in their winds. (ANI)

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