Su­per­nova Smash

Air & Space Smithsonian - - Chatter -

Type 1a su­per­novas are im­por­tant in the study of the uni­verse. Each of these white dwarfs— dead stars that no longer have fu­sion re­ac­tions—ac­cu­mu­lates ma­te­rial from a com­pan­ion star un­til the white dwarf reaches a cer­tain mass limit, then re-ig­nites vi­o­lently in a su­per­nova. The pre­dictable bright­ness of the ex­plo­sions en­ables cos­mol­o­gists to use them as “stan­dard can­dles,” to com­pare with other ob­jects in the uni­verse. But mys­ter­ies abound about what makes up the com­pan­ion star, which is de­stroyed by the ex­plo­sion.

Astronomers re­cently used NASA’S Swift gamma-ray ob­ser­va­tory to watch a su­per­nova just as it ig­nited and smashed into its com­pan­ion, giv­ing off a sig­na­ture ul­tra­vi­o­let light in­di­cat­ing that the com­pan­ion was another white dwarf.

Coin­ci­den­tally, another su­per­nova’s com­pan­ion, re­cently found on pre-ex­plo­sion Hub­ble im­ages, was iden­ti­fied as a red gi­ant. Said Swift study as­tronomer An­drew How­ell, “No won­der we’ve been so con­fused.... Ap­par­ently you can blow up stars in two dif­fer­ent ways and still get nearly iden­ti­cal ex­plo­sions.”

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