What characterizes a type-1 supernova?

A type-1 supernova, specifically known as Type Ia, is characterized by the thermonuclear explosion of a white dwarf star. This process typically occurs in a binary star system where the white dwarf accretes material from a companion star, which is often a red giant. As the white dwarf accumulates this gas, it eventually reaches a critical mass known as the Chandrasekhar limit, leading to an uncontrollable fusion reaction that results in a catastrophic explosion.

This mechanism for type-1 supernovae is distinct because it does not involve the rapid core collapse of a massive star, which is the process characteristic of type-II supernovae. Instead, the white dwarf in a type-Ia event is often stable until the influx of material tips the balance, triggering the explosive reaction. Thus, the process of accretion and subsequent explosive runaway fusion uniquely defines type-1 supernovae.