What specific class of stellar remnant is responsible for seeding the interstellar medium with elements heavier than iron?

Answer

Supernova remnants

The explosive aftermath of massive stars (supernovae) ejects all elements created in the star’s core that are heavier than iron, enriching the surrounding space.

What specific class of stellar remnant is responsible for seeding the interstellar medium with elements heavier than iron?
SpaceastronomycompositionnebulaElements