Depending on the star's size, a supernova explosion can leave behind a neutron star, also known as a pulsar, or a black hole. A pulsar is an extremely dense ball of neutrons 10 to 20 miles in diameter that can rotate over 700 times per second. read more
After a supernova explosion an assortment of elements including elements above iron in the periodic table are created. Along with gasses and, depending, on the mass and energy of the star a blackhole. read more
During a supernova, if a star is massive enough for its gravity to overcome neutron degeneracy pressure in the core, the core will collapse to a black hole. read more