If the collapsing stellar core at the center of a supernova contains the right amount of mass, the collapse continues until electrons and protons combine to form neutrons. (educationworld.com)
H. Bond (STSci), R. Ciardullo (PSU), WFPC2, HST, NASA CM Draconis B is a white dwarf (a remnant stellar core which enriched its binary companions, Stars Aab, with elements heavier than hydrogen when it cast off its outer gas layers) like planetary nebula NGC 2440. (solstation.com)
«What probably happens is that after the supernova, the remaining stellar core collapses under its own gravity to form a black hole,» Reeves says. (discovermagazine.com)