Don't show me this message again✕ A strange yellow star which exploded into a supernova in a never-before-seen situation “stretches what’s physically possible”, scientists have said. A team at Nasa was monitoring the enigmatic ball of gas for 30 months before it exploded into a supernova. Burning 35 million light years from the Earth, what should have been routine behaviour for this star turned into something unexpected: unlike others, this did not have a layer of hydrogen around it before it exploded, which scientists did not realise was achievable. “We haven’t seen this scenario before,” said Northwestern’s Charles Kilpatrick, who led the study. “If a star explodes without hydrogen, it should be extremely blue — really, really hot.