Science and Technology @ UCSB
Supernovae, the explosions of stars, have been observed by the thousands. And in all cases, the transient astronomical events signaled the death of those stars. Now, astrophysicists at UC Santa Barbara and astronomers at Las Cumbres Observatory (LCO) have reported a remarkable exception: a star that exploded multiple times over a period of more than 50 years. Their observations, published in the journal Nature, are challenging existing theories on these cosmic catastrophes.
“This supernova breaks everything we thought we knew about how they work,” said lead author Iair Arcavi, a NASA Einstein postdoctoral fellow in UC Santa Barbara’s Department of Physics and at LCO. “It’s the biggest puzzle I’ve encountered in almost a decade of studying stellar explosions.”
When iPTF14hls was discovered in September 2014 by the Caltech-led Palomar Transient Factory, it looked like an ordinary supernova. But several months later, the scientific team noticed that the supernova, once faded, was growing brighter. It was a phenomenon they had never seen before.
A normal supernova rises to peak brightness and fades over 100 days. Supernova iPTF14hls, on the other hand, grew brighter and dimmer at least five times over three years.
When the scientists examined archival data, they were astonished to find evidence of an explosion in 1954 at the same location. Somehow this star survived that explosion and then exploded again in 2014. In the study, the authors calculated that the exploding star was at least 50 times more massive than the sun and probably much larger.
“Supernova iPTF14hls may be the most massive stellar explosion ever seen,” explained co-author Lars Bildsten, director of UCSB’s Kavli Institute for Theoretical Physics. “For me, the most remarkable aspect of this supernova was its long duration, something we have never seen before. It certainly puzzled all of us as it just continued shining.” As part of this effort, Bildsten worked with …
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