What happens when a massive star dies?

The answer

When a star more than eight times the Sun's mass exhausts its nuclear fuel, its core collapses in milliseconds under its own gravity. The infalling material bounces off the ultra-dense core and creates a massive shockwave that tears the star apart in a supernova, briefly outshining its entire galaxy with the luminosity of billions of suns. The explosion scatters heavy elements like gold, uranium, and iron into space - seeding future generations of stars and planets. The remaining core becomes either a neutron star or, if massive enough, a black hole.