(original) (raw)

image/svg+xml The progenitor of a Type Ia supernova Two normal starsare in a binary pair. The more massivestar becomes a giant... ...which spills gas onto thesecondary star, causing it toexpand and become engulfed. The remaining core ofthe giant collapses andbecomes a white dwarf. The common envelope isejected, while the separationbetween the core and thesecondary star decreases. The secondary, lighter starand the core of the giantstar spiral toward withina common envelope. ...causing the companionstar to be ejected away. The white dwarf's massincreases until it reaches acritical mass and explodes... The aging companionstar starts swelling, spillinggas onto the white dwarf.