Dy­ing star makes stel­lar come­back

The Progress-Index Weekend - - OPINION - By Mar­cia Dunn

CAPE CANAVERAL, Fla. — Death def­i­nitely be­comes this star.

Astronomers re­ported Wed­nes­day on a mas­sive, dis­tant star that ex­ploded in 2014 — and also, ap­par­ently back in 1954. This is one su­per­nova that re­fuses to bite the cos­mic dust, con­found­ing sci­en­tists who thought they knew how dy­ing stars ticked.

The oft-erupt­ing star is 500 mil­lion light-years away — one light-year is equal to 5.9 tril­lion miles — in the di­rec­tion of the Big Bear con­stel­la­tion. It was dis­cov­ered in 2014 and, at the time, re­sem­bled your ba­sic su­per­nova that was get­ting fainter.

But a few months later, astronomers at the Cal­i­for­nia-based Las Cum­bres Ob­ser­va­tory saw it get­ting brighter. They’ve seen it grow faint, then bright, then faint again five times. They’ve even found past ev­i­dence of an ex­plo­sion 60 years ear­lier at the same spot.

Su­per­novas typ­i­cally fade over 100 days. This one is still go­ing strong af­ter 1,000 days, al­though it’s grad­u­ally fad­ing.

“It’s very sur­pris­ing and very ex­cit­ing,” said as­tro­physi­cist Iair Ar­cavi of the Univer­sity of Cal­i­for­nia, Santa Bar­bara who led the study. “We thought we’ve seen ev­ery­thing there is to see in su­per­novae af­ter see­ing so many of them, but you al­ways get sur­prised by the uni­verse. This one just re­ally blew away ev­ery­thing we thought we un­der­stood about them.”

The su­per­nova — of­fi­cially known as iPTF14hls — is be­lieved to have once been a star up to 100 times more mas­sive than our sun. It could well be the big­gest stel­lar ex­plo­sion ever ob­served, which might ex­plain its deathde­fy­ing pe­cu­liar­ity.

It could be mul­ti­ple ex­plo­sions oc­cur­ring so fre­quently that they run into one an­other or per­haps a sin­gle ex­plo­sion that re­peat­edly gets brighter and fainter, though sci­en­tists don’t know ex­actly how this hap­pens.

One pos­si­bil­ity is that this star was so mas­sive, and its core so hot, that an ex­plo­sion blew away the outer lay­ers and left the cen­ter in­tact enough to re­peat the en­tire process.

But this pul­sat­ing star the­ory still doesn’t ex­plain ev­ery­thing about this su­per­nova, Ar­cavi said.

Har­vard Univer­sity’s as­tron­omy chair­man, Avi Loeb, who was not in­volved in the study, spec­u­lates a black hole or mag­ne­tar — a neu­tron star with a strong mag­netic field — might be at the cen­ter of this never-be­fore-seen be­hav­ior. Fur­ther mon­i­tor­ing may bet­ter ex­plain what’s go­ing on, he said.

Las Cum­bres , a global net­work of ro­botic tele­scopes, con­tin­ues to keep watch.

Sci­en­tists do not know whether this par­tic­u­lar su­per­nova is unique; it ap­pears rare since no oth­ers have been de­tected.

“We could ac­tu­ally have missed plenty of them be­cause it kind of mas­quer­ades as a nor­mal su­per­nova if you only look at it once,” Ar­cavi said.

Noth­ing lasts for­ever — not even this su­per su­per­nova.

“Even­tu­ally, this star will go out at some point,” Ar­cavi said. “I mean, en­ergy has to run out even­tu­ally.”

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