부산대학교 도서관

Primed to explode Type Ia supernovae are exploding stars used to measure the expansion of the Universe. They are important to us as they are responsible for the production of most of the iron in the Universe. Exactly what object is exploding and why is unclear — though a white dwarf in a binary system is the likely candidate — and indirect methods of identifying progenitors have failed. Rasmus Voss and Gijs Nelemans now report the direct observation of a progenitor of a supernova that exploded on 5 November 2007. They unearthed an object in the exact position of supernova 2007on in images taken by the Chandra X-ray telescope four years before the explosion. Deep optical images from the archives show nothing in this position. This seems to favour the accretion model for this supernova, where a white dwarf accretes material from a companion star, rather than a merger of two white dwarfs.