Type Ia supernovae are bright “standard candles” for measuring cosmic distances. Standard enough to discover dark energy, they’re far from identical. Researchers at the Berkeley Lab-based Nearby Supernova Factory have shown that supernova twins with closely matching spectra double the accuracy of distance measures.
Until recently, scientists thought they knew why Type Ia supernovae – the best cosmological “standard candles” – are all so much alike. But their favorite scenario was wrong. White dwarfs don’t all reach the Chandrasekhar limit, 1.4 times the mass of our sun, before they detonate in a massive thermonuclear explosion. Most Type Ia progenitors are less massive, and a few are even more massive. New work by the Berkeley Lab-based Nearby Supernova Factory can identify which theories of the strange circumstances that lead to a Type Ia explosion actually work and which don’t.