TOOL #19: STAR DEATH All things die, and stars are no exception. Remember that if a star has a little more mass, it burns through its fuel much faster. When a star begins to die, there are just two rules to remember: When non-fusing "ash" builds up in the core, the star expands. When a star expands, its atmosphere cools down (and when it shrinks, its atmosphere heats up) The star has been stably fusing hydrogen into helium for its whole life. The helium that is created in the star sinks to the center of the core as "ash" since the temperatures and pressures in the core of a main sequence star aren't high enough to fuse the helium into carbon. When enough ash builds up in the core, convection processes begin to dominate in the star. Convection is heated bubbles of plasma that rise and sink in the star's atmosphere like a lava lamp. Convection cells rise up and push the surface of the star outward, almost like blowing up a balloon. Convection causes the star to produce an extremely stron