01:750:109 Chapter Notes - Chapter 9.1: Thermal Energy, Energy Economics, Protostar
Document Summary
Story of star life is like the story of a battle between two opposing forces: pressure and gravity. Star is born when gravity becomes strong enough to overcome pressure within a gas cloud and compress it until nuclear fusion begins. A star lives while the energy generated by fusion can keep pressure and gravity in steady balance to prevent star from expanding or contracting. A star dies as it exhausts its fuel for fusion and goes out of balance again. This section examines how a star achieves the steady state of balance that fusion maintains. Stars form out of interstellar gas, within clouds in which the inward pull of gravity becomes stronger than the outward push of gas pressure. 2 things help gravity win out over pressure and start the contraction of a gas cloud: Bc packing the gas particles closer together makes the gravitational force between them stronger. Bc lowering a cloud"s temperature reduces the gas pressure.
