I think it's type 1a. There was a discussion on this recently after a new supernova observation. https://news.ycombinator.com/item?id=7104056 https://news.yco

I think it's type 1a. There was a discussion on this recently after a new supernova observation. https://news.ycombinator.com/item?id=7104056 https://news.ycombinator.com/item?id=7104056 Basically it's unknown if it is a two star system where the neutron consumes the partner, or a three star system where two neutron stars collide head on.