Astronomers have long had the tools to detect the signature of this fusion, but had to wait for a supernova to explode nearby in order to begin their observations.
Towards the end of its life, a star with the mass of the Sun will shed its outer layers as its core shrinks down to become a white dwarf. Left to their own devices, single white dwarfs will just cool off slowly over time.
But there is a maximum mass at which a white dwarf can remain stable - a property known as the Chandrasekhar limit, after the Indian-American astrophysicist Subrahmanyan Chandrasekhar.
If a white dwarf steals matter from a stellar companion, or collides with another white dwarf, the extra weight can compress the carbon in the star's core until this element undergoes nuclear fusion.
The carbon is fused into heavier elements with a sudden release of energy that tears the star apart.
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