Type Ia supernovae are a cornerstone of extragalactic distance measurements, so it’s important that we understand them very well. Right now, we’re fairly certain that Type Ia supernovae are the result of white dwarfs exploding. But how they explode is still an open question.
To Explode a White Dwarf
A creation mechanism for Type Ia supernovae where a white dwarf accretes mass from a companion (upper panel) till it explodes as a supernova (lower panel). [NASA/CXC/M. Weiss]White dwarfs are remnants of relatively low-mass stars like our Sun. They are essentially exposed stellar cores, typically dominated by carbon and oxygen with an outer layer of helium. White dwarfs don’t produce energy of their own. Instead, they just cool off, slowly radiating away residual energy from when they were part of a star.
So how do you make something like a white dwarf explode? Just add mass! If a white dwarf accretes enough matter from a nearby companion, it can approach the Chandrasekhar limit of 1.4 solar masses and explode. This process seems fairly straightforward, but it turns out there are several potential ways to explode a white dwarf.
One scenario involves “double detonation”, where the helium shell of a white dwarf ...