Two white dwarfs collide, may end up as neutron star

Enlarge / Two white dwarfs pondering a merger. (credit: NASA/JPL-Caltech)

It seems like you can’t go a day without hearing news of a merger. Not corporate mergers—those are boring. Mergers between astronomical bodies are where it’s at these days. And it’s not just black holes and neutron stars doing the merging. I honestly had no idea, but it seems that it is not so unusual for stars to be the product of a merger.

Of course, it’s also possible that a collision between two stars would lead to a massive explosion. And, so far at least, it’s been hard to answer the question of what happens when two stars collide: do they explode or go out with a whimper? The observation of a large white dwarf that seems to have been the product of two titchy white dwarfs may support the whimper side.

Stellar end-times 

When stars run out of fuel, their mass determines their fate. Very large stars end spectacularly. The star collapses in on itself, followed by a violent explosion—no going silently into the night around here. As the stellar dust settles, the remains include a neutron star or a black hole. This is the ending for show-offs.