How will a massive star change at the end of the main stable period?

Question

Ivy Allen · Accepted Answer

When a massive star runs out of fuel it undergoes core collapse and explodes as a supernova.

When a star's core is mostly iron, fusion can no longer occur because fusing iron requires energy rather than releasing it, as is the case with lighter elements. Stars larger than about 8 solar masses are capable of fusing increasingly heavy elements. Following the cessation of fusion, the iron core collapses under gravity to form a black hole or a neutron star. The energy released during the core collapse ignites fusion reactions in the lighter elements surrounding the core. The star undergoes a supernova explosion, which results in a brief burst of intense brightness, as the fusion reactions in the layers surrounding the core quickly consume enormous amounts of material. All that's left is a massive cloud of material from the rest of the star and the neutron star, also known as a black hole.

Elena Antonova · Answer

undefined A massive star will experience a number of changes during the end of its main sequence life, such as the expansion of its outer layers, the depletion of hydrogen fuel in its core, and the onset of helium fusion in its core, which will result in the formation of either a blue or red supergiant, depending on the star's initial mass.