What characteristic observed in a supernova spectrum helps distinguish it from a core-collapse event?

Answer

The absence of hydrogen lines in the spectrum.

Astronomers classify explosions based on spectral signatures; core-collapse events often retain some hydrogen envelopes, whereas thermonuclear explosions, like Type Ia, frequently lack hydrogen lines.

What characteristic observed in a supernova spectrum helps distinguish it from a core-collapse event?
astronomystellar evolutionsupernovastar deathviolent