PCS 181 Study Guide - Midterm Guide: Triple-Alpha Process, Helium Flash, Coronal Mass Ejection
Document Summary
Most stars are main sequence stars: stars that are living. At the start of a star"s life it is at ten million kelvin. A star does not live forever: our sun is middle aged right now. When star is born, key moment is fusion ignition. When star dies, key moment is the end of fusion. Nuclear fusion: needs high temperature and high pressure this happens at center of the sun, protons are moving super fast and they fuse. Hydrogen fusion: is called the proton-proton chain: hydrogen collide to form deuterium, finally we get helium and there is a mass defect because extra mass is converted entirely into energy. Bigger stars burn hotter and brighter but burns out really fast: more massive stars have more gravity. More central temperature: puts out more light, lives much shorter lives why doesn"t the sun explode? there is soo much pressure at the centre of the sun, however this pressure decreases going outwards.