PHYS 183 Study Guide - Midterm Guide: Protostar, Red Giant, Main Sequence
Document Summary
Main sequence turn-off: precise point on the hr diagram that stars diverge from main sequence. Nuclear fusion moves a protostar to a main sequence star. Degeneracy pressure: pressure that is density dependent. Brown dwarf star: failed stars due to electron degeneracy pressure halting collapse before fusion begins so slowly cool & fade away. Radiation pressure (pressure exerted by photons: above ~150 msun there are so many photons they blow star apart. Chapter 17: star stuff low mass stars: main sequence giant supergiant white dwarf, main sequence giant. Main sequence stars burn h slow & steady & fuses it in the core. When all h in core is burned, have inert he in the core no more pressure to support against gravity so star collapses. Once he runs out, star collapses & leaves he & h burning shells around c & o core. C fusion requires very high temperatures can"t be reached before degeneracy pressure stable core is exposed.