Saturday, January 11, 2014

New Images Show Supernova Dust Production

For decades, scientists have suspected supernovae create much of the dust that powers galactic formation. Striking new observations with the Atacama Large Millimeter Array (ALMA) telescope capture, for the first time, the remains of a recent supernova brimming with freshly formed dust. If enough of this dust makes the perilous transition into interstellar space, it could explain how many galaxies acquired their dusty, dusky appearance.

astronomy, supernova, telescope, oxygen, carbon, silicon, galaxy

Galaxies can be remarkably dusty places and supernovae are thought to be a primary source of that dust, especially in the early Universe. But direct evidence of a supernova's dust‐making capabilities has been slim up to now, and could not account for the copious amount of dust detected in young, distant galaxies. But now observations with ALMA are changing that.

"We have found a remarkably large dust mass concentrated in the central part of the ejecta from a relatively young and nearby supernova," said Remy Indebetouw, an astronomer at the National Radio Astronomy Observatory (NRAO) and the University of Virginia, both in Charlottesville, USA. "This is the first time we've been able to really image where the dust has formed, which is important in understanding the evolution of galaxies."

An international team of astronomers used ALMA to observe the glowing remains of Supernova 1987A, which is in the Large Magellanic Cloud, a dwarf galaxy orbiting the Milky Way about 160 000 light‐years from Earth. SN 1987A is the closest observed supernova explosion since Johannes Kepler's observation of a supernova inside the Milky Way in 1604.

Astronomers predicted that as the gas cooled after the explosion, large amounts of dust would form as atoms of oxygen, carbon, and silicon bonded together in the cold central regions of the remnant. However, earlier observations of SN 1987A with infrared telescopes, made during the first 500 days after the explosion, detected only a small amount of hot dust.

With ALMA's unprecedented resolution and sensitivity, the research team was able to image the far more abundant cold dust, which glows brightly in millimetre and submillimetre light. The astronomers estimate that the remnant now contains about 25 percent the mass of the Sun in newly formed dust. They also found that significant amounts of carbon monoxide and silicon monoxide have formed.

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