Evolution of a Massive Star

A massive star has a mass greater than about 10 solar masses. Its strong gravity gives it a very hot core, so it fuses hydrogen quickly and has a short main sequence lifetime.When the hydrogen in its core runs out, the core contracts and heats up while the outer layers expand enormously. The star becomes a red supergiant.Because the core is so massive, gravity can compress it to much higher temperatures than in a low-mass star. It fuses helium, then carbon, neon, oxygen and silicon in turn, building up heavier and heavier elements. The core develops layers like an onion, with the heaviest elements at the centre.Fusion stops at iron. Iron has one of the highest binding energies per nucleon, so fusing iron nuclei would absorb energy rather than release it. With no energy released in the core, there is no radiation pressure to support it against gravity.The iron core collapses suddenly. The outer layers fall inwards, rebound off the extremely dense core and are blasted out into space in a supernova. For a short time a supernova can be brighter than a whole galaxy. Elements heavier than iron are made in the supernova and scattered into space, where they can later become part of new stars and planets.What is left of the core becomes either a neutron star or a black hole, depending on its mass.main sequence star → red supergiant → supernova → neutron star or black hole