Thursday, November 9, 2017

Astronomers Find Star That Went Supernova Multiple Times

Artist’s impression of a Supernova. Image Credit NASA, ESA, G. Bacon (STSci)
Artist’s impression of a Supernova. Image Credit NASA, ESA, G. Bacon (STSci)
 Astronomers at the University of California Santa Barbara (UCSB) and Las Cumbres Observatory (LCO) have discovered a star that exploded multiple times over a period of more than fifty years. This discovery challenges the existing theory that when a supernova occurs, the cosmic event marks the death of a star.
 The supernova, named iPTF14hls, was first discovered back in September 2014 by the Palomar Transient Factory. At the time it appeared to be any other supernova, however, in recent months, LCO astronomers have noticed something unheard of - the supernova was growing brighter again after it faded.
 When astronomers checked the archival data, they were astonished to discover evidence of a similar explosion in 1954 that occurred in the same location. “This supernova breaks everything we thought we knew about how they work. It’s the biggest puzzle I’ve encountered in almost a decade of studying stellar explosions," said Dr. Iair Arcavi of the UCSB and LCO.
 Supernova iPTF14hls may be the first example of 'Pulsational Pair Instability Supernova.' This theorized supernova is thought to be created when massive stars become so hot in their cores that energy is converted into matter and antimatter. This causes an explosion that regularly blows off the outer layers of the star while leaving the core intact; this process repeats over the decades until culminating in a final large explosion and collapse to a black hole.
“These explosions were only expected to be seen in the early universe and should be extinct today," said Andy Howell, leader of the LCO supernova group and co-author of the study. "This is like finding a dinosaur still alive today. If you found one, you would question whether it truly was a dinosaur.”

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