ASTR 1100 Lecture Notes - Lecture 15: Low Mass, Solar Mass, Planetary Nebula
Document Summary
Lecture 15: types of stars: low mass stars. Scientists separated stars into two categories: low mass stars, high mass stars, evolution of low mass star. Hydrogen fuses into helium in the star"s core. Sun => lifetime is 10 billion years. Small stars lives approximately more than 10 billion years, shorter time for more massive ones. Some stars fuse hydrogen into helium depending on their mass. The entire core becomes helium and needs a very high temperature for helium fusion to start (100 mil k needed). Needs high temperature to slam those positive charges together. Red giant occurs when the hydrogen shell is burning. => there are lots of outward radiation pressures from the shell and this will result for the star to expand tremendously. Once the sun reaches 10 billion years, it will be the end of life on earth and the sun will swallow mercury & venus (earth"s surface melts).
