Question

What do you call a huge exploding star that ejects most of its mass

Answer 1

Some types of stars expire with titanic explosions, called supernovae.

When a star like the Sun dies, it casts its outer layers into space, leaving its hot, dense core to cool over the eons. But some other types of stars expire with titanic explosions, called supernovae. A supernova can shine as brightly as an entire galaxy of billions of "normal" stars. Some of these explosions completely destroy the star, while others leave behind either a super-dense neutron star or a black hole -- an object with such powerful gravity that not even light can escape from it.