What is a Type Ia supernova?
Quick Answer
A Type Ia supernova is a powerful stellar explosion that happens when a white dwarf undergoes runaway fusion. It produces a very bright and relatively standard peak brightness.
The Full Story
Type Ia supernovae occur in binary systems when a white dwarf accretes matter from a companion or merges with another white dwarf, pushing it toward a thermonuclear explosion. Because their peak luminosities are similar, astronomers use them as “standard candles” to measure cosmic distances. This method was crucial in the 1998 discovery that the Universe’s expansion is accelerating. Type Ia events are also important sources of iron and other heavy elements in galaxies.
Key Facts
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"The stellar explosions that changed our picture of the Universe"