AST 112 Study Guide - Midterm Guide: Stellar Parallax, Parsec, Binding Energy
Document Summary
Energy from the sun comes from nuclear fusion. Binding energy keeps the protons and neutrons in the nucleus from flying apart. Nuclear fusion requires high temperatures to overcome the coulomb barrier. (nuclei all have positive electric charges and so they repel each other) High densities are needed so that ther e are sufficient collisions between nuclei. The proton-proton chain reaction is one of several fusion reactions by which stars convert hydrogen to helium. The proton-proton chain dominates in stars the size of the sun or smaller. Neutrinos are elementary particles that often travel close to the speed of light, lack an electric charge, are able to pass through ordinary matter almost undisturbed and are thus extremely difficult to detect. The positron or anti-electron is the anti-particle or the anti-matter counterpart of the electron. The positron has an electric charge of +1, a spin of 1/2, and the same mass as an electron.
