Final answer:
The compact remnant of a high mass star after a supernova is either a neutron star or a black hole, depending on whether the core mass is less than or greater than about 3 solar masses (Msun).
Step-by-step explanation:
The compact corpse of a high mass star left over after a supernova, depending on the mass of the core, can be either a neutron star or a black hole. A white dwarf is the remnant of a less massive star that has a core mass less than about 1.4 times that of our Sun (the Chandrasekhar limit). In contrast, a neutron star forms after a supernova explosion if the core mass is between about 1.4 and 3 solar masses (Msun). If the core's mass is more than about 3 Msun, the object will continue to collapse, becoming a black hole. White dwarfs are typically made of helium, carbon and oxygen, or oxygen, neon, and magnesium, depending on the original star's mass. Ultimately, all these objects become difficult to observe as they cool and emit less radiation.