What happens to the core when the time passes and it runs out of helium? What happens to the rest of the star?
a) It collapses and starts burning carbon
b) It expands and becomes a red giant
c) It explodes in a supernova
d) It remains stable and continues burning helium
What happens to the rest of the star when the core runs out of helium?
a) It collapses into a black hole
b) It loses its outer layers and forms a planetary nebula
c) It expands into a red supergiant
d) It stops nuclear fusion and becomes a white dwarf
