Puzzling new Supernova

Monday, November 13, 2017

An exploding star that continued to shine for nearly two years — unlike most supernovae, which fade after a few weeks — is puzzling astronomers and leading theorists, including UC Berkeley astrophysicist Daniel Kasen, to suggest that the event may be an example of a star so hot that it produces antimatter in its core.

Stars would have to be very massive to get this hot, Kasen said, which is why most astronomers assumed they existed, if at all, only in the early years of the universe.

But evidence that the star underwent repeated eruptions make “something along these lines seem most plausible,” he said. Kasen, an associate professor of physics and of astronomy and a scientist at Lawrence Berkeley National Laboratory, is a coauthor of a paper describing the weird exploding star published this week in the British journal Nature.

“It is possible that this was the result of star so massive that it was capable of generating pairs of anti-electrons and electrons in its core,” Kasen said. “That would cause the star to go through phases of violently instability, resulting in a series of bright eruptions.”

Another co-author, Peter Nugent, a senior staff scientist in the Computational Research Division at Berkeley Lab and an adjunct professor of astronomy at UC Berkeley, helped lead observations of the exotic star explosion at the W.M. Keck Observatory in Hawaii.

“This is one of those head-scratcher type of events,” he said. “At first we thought it was completely normal and boring. Then it just kept staying bright, and not changing, for month after month. Piecing it all together … has started to shed light on what this could be. However, I’d really like to find another one.”

The study was led by Iair Arcavi, a NASA Einstein postdoctoral fellow at UC Santa Barbara and Las Cumbres Observatory in Goleta, California.

 

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Robert Sanders
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