This is a truly weird one, a supernova that do explode not just once - but several times. iPTF14hls went boom in 1954, then again in 2014 - and it's still shining bright.
One of the possible solutions to this remarkable behaviour is that the star might be so massive it got antimatter in the core - though even that hypothesis might not be enough to fully explain the stars behaviour.
Don't trust me on this one, here's what Andy Howell, leader of the LCO supernova group and co-author said about this matter:
“These explosions were only expected to be seen in the early universe and should be extinct today. This is like finding a dinosaur still alive today. If you found one, you would question whether it truly was a dinosaur.”
Keck observatory link to press release.
Abstract in Nature.