Maggie McKee writes "Astronomers have spotted the brightest supernova ever seen — it is intrinsically two to three times brighter than any previously recorded. It has many characteristics of a type Ia explosion, but has hydrogen in its spectrum, unlike other type Ia's. That suggests that this supernova resulted from the collision of two stars — most likely a white dwarf and a red giant — rather than from an exploding white dwarf. If so, it might affect the interpretation of previous cosmological studies that depend on type Ia 'standard candle' observations, like dark energy. But other astronomers say merger-triggered explosions are probably rare and therefore won't throw a wrench in the works."