Astronomy 1021 Lecture Notes - Lecture 18: Escape Velocity, Event Horizon, Triple-Alpha Process

• School: Western University
• Department: Astronomy
• Course: Astronomy 1021
• Professor: Jan Cami

Document Summary

All elements heavier than lithium were made in stars. All elements heavier than iron were made in a supernova explosion. Elements are retuned to the galaxy from stars in stellar winds and in supernovas. Elements less massive then fe, fusion releases energy. To make elements more massive than fe requires energy. Iron is the end of the road for massive stars. With no more fusion in the core the upper layers fall in, crunch the core down until it becomes degenerate and then bounces back explosively. Helium fusion can make carbon in low mass stars. Binary systems - two or more stars that orbit their center of mass. More massive components turn off the main sequence rst. White dwarfs are remnants of low mass stars. Neutron stars are remnants of high mass stars. Composed of helium for the lowest mass white dwarfs, primarily carbon for sun like stars and carbon/oxygen for intermediate mass stars.