MYS­TE­RI­OUS ZOM­BIE STAR KEEPS EX­PLOD­ING, BUT WON’T DIE

BBC Earth (Asia) - - Update | The Latest Intelligence -

Mor­ris­sey was right – there is a light that never goes out! An in­ter­na­tional team of as­tronomers has made a bizarre dis­cov­ery: a star that has ex­ploded re­peat­edly, yet car­ries on shin­ing.

When stars of a cer­tain size reach the end of their life­cy­cle, they ex­plode in en­er­getic cos­mic events known as su­per­novae. Such ex­plo­sions have been recorded by as­tronomers thou­sands of times, and in ev­ery recorded case, such an ex­plo­sion has marked the death of a star. But now sci­en­tists seem to have found an ex­cep­tion in iPTF14hls, a su­per­nova that has ex­ploded at least twice in the past 70 years.

“This su­per­nova breaks ev­ery­thing we thought we knew about how they work. It’s the big­gest puz­zle I’ve en­coun­tered in al­most a decade of study­ing stel­lar ex­plo­sions,” said Dr Iair Ar­cavi of Las Cum­bres Ob­ser­va­tory.

iPTF14hls was dis­cov­ered in 2014 by re­searchers at Cal­tech. At first it ap­peared nor­mal, but seven months af­ter it faded it be­gan grow­ing in bright­ness. When as­tronomers went back and looked at archival data, they found ev­i­dence of an ex­plo­sion in 1954 at the same lo­ca­tion. The star has some­how sur­vived the first ex­plo­sion, only to ex­plode again in 2014.

One po­ten­tial ex­pla­na­tion has to do with the star’s mass. Hav­ing at least 50 times the mass of our Sun, it could have been big enough to be the first ex­am­ple of a the­o­rised event known as a Pul­sa­tional Pair In­sta­bil­ity Su­per­nova – a star so mas­sive and hot that it cre­ated an­ti­mat­ter at its core, which in turn caused it to un­dergo re­peated ex­plo­sions.

“This is one of those head-scratcher type of events,” said Dr Pe­ter Nu­gent. “At first we thought it was com­pletely nor­mal and bor­ing. Then it just kept stay­ing bright, and not chang­ing, for month af­ter month. I would re­ally like to find another one like this.”

Su­per­novae are sup­posed to only hap­pen once, but try telling iPTF14hls that

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