The star that would not die

An event that initially resembled an ordinary supernova explosion continued to erupt brightly for more than 600 days. Standard theoretical models cannot explain the event's properties. See Letter p.210 A very unusual supernova Thousands of 'core-collapse' supernovae have been observed over the past 15 years, with common observational elements such as hydrogen absorption lines that slow over time and a single light-curve peak or luminosity that plateaus for around 100 days before declining. Iair Arcavi and colleagues report observations of the supernova iPTF14hls, which does not display the usual elements. Its light curve has multiple peaks and extends over 600 days. They conclude that the properties could be explained by ejection of several tens of solar masses of gas a few hundred days before the explosion, but there is no viable explanation for how this occurred. Although multiple pre-supernova eruptions are predicted by the pulsational pair instability, that model is inconsistent with the energetics involved here and the continued presence of hydrogen absorption lines with no decrease in velocity.