A supernova that stayed bright for over three years seemed impossible, but it could be explained if the explosion is running into dense rings of dust and gas
The strange supernova that just kept exploding may not be quite so weird, after all.
Most supernovae brighten once as they explode and then fade, but one that was first spotted three years ago has brightened five times so far and has only just started to dim over the past few months. Researchers thought it might be a new kind of explosion, but new observations show it might be a regular supernova whose light is lent extra power by a dense disc of debris.
Iair Arcavi at University of California, Santa Barbara, and his colleagues first saw supernova iPTF4hls in September 2014 and noticed that while its light spectrum was fairly normal, it was far brighter and longer-lasting than expected.
To figure out what was causing this supernova’s weirdness, Jennifer Andrews and Nathan Smith at the University of Arizona in Tucson