AST201H5 Lecture Notes - Lecture 10: Brown Dwarf, Solar Mass, Outer Core
Document Summary
Stars in a cluster share: 1) same distance for earth, 2) same composition, 3) same age. A clusters age: learned from the main sequence"s length. Stars are still forming today from huge interstellar clouds of very cold, dark gas/dust. A cloud contracts fragments -> clusters of stars. Few high mass, many medium mass, huge number of low mass stars. Contracting gas converts stored energy into heat -> fusion stars. Jets and multiple stars distribute the energy and momentum. Above 100 msun the fusion is too much for the star to contain. Below 0. 1 msun fusion cannot start -> brown dwarf. A star"s life depends on the fusion energy in its core, but that is not observable. Must use theory (gravity -> pressure -> fusion -> energy and heat -> pressure, ) Use a computer to calculate how the star changes with time as fusion converts h. > density changes -> pressure changes -> temp changes -> fusion changes.
