| Back | Where a star’s mass in is excess of 10 M☉, its evolution takes a different path. As hydrogen supplies deplete, the temperature is high enough for helium fusion in to heavier elements to take place, forming a red supergiant. The red supergiant has layers of increasingly heavy elements produced from fusion, with an inert iron core (as iron fusion does not release energy, it is unable to fuse further). Once the iron core is produced, the star becomes unstable. A type 2 supernova occurs where there is a shockwave which ejects the materials in the outer shells out in to space, and the core collapses. Any elements heavier than iron are formed in supernovas. If the remaining core mass is greater than 1.44M☉, protons and electrons combine to form neutrons. This produces an extremely small, dense neutron star. If the remaining core mass is greater than 3M☉, the gravitational forces are so strong that the escape velocity of the core is greater than the speed of light. This is a black hole, which even photons cannot escape. |