Star that exploded over 50-yr period discovered by astronomers

A study published in the journal Nature by a group of astronomers has announced the discovery of a star that exploded multiple times over a period of more than fifty years.

Their observations, which include data from W. M. Keck Observatory on Maunakea, Hawaii, are challenging existing theories on these cosmic catastrophes.

“The spectra we obtained at Keck Observatory showed that this supernova looked like nothing we had ever seen before. This, after discovering nearly 5,000 supernovae in the last two decades,” said Peter Nugent, Senior Scientist and Division Deputy for Science Engagement in the Computational Research Division at Lawrence Berkeley National Laboratory who co-authored the study.

“While the spectra bear a resemblance to normal hydrogen-rich core-collapse supernova explosions, they grew brighter and dimmer at least five times more slowly, stretching an event which normally lasts 100 days to over two years.”

Researchers used the Low Resolution Imaging Spectrometer (LRIS) on the Keck I telescope to obtain spectrum of the star’s host galaxy, and the Deep Imaging and Multi-Object Spectrograph (DEIMOS) on Keck II to obtain high-resolution spectra of the unusual star itself.

The supernova, named iPTF14hls, was discovered in September of 2014 by the Palomar Transient Factory. At the time, it looked like an ordinary supernova. Several months later, LCO astronomers noticed the supernova was growing brighter again after it had faded.