Whose observations first showed that stars can explode and seed the universe with heavy elements?

In the 1930s, Walter Baade and Fritz Zwicky proposed that supernovae are a distinct, extremely powerful class of stellar explosion. They argued that these events could produce neutron stars and account for large amounts of cosmic energy. Modern astronomy confirms that supernovae forge and disperse many heavy elements, such as iron and elements beyond it. Their work helped establish supernovae as key engines of chemical enrichment in the universe.