AST201H1 Lecture Notes - Lecture 5: Solar Wind, Convection Zone, Gravitational Energy

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST201H1
• Professor: Ian Shelton

Document Summary

Radius- over 100x bigger than the earth in diameter. Is it on fire? chemical energy content / luminosity = 10,000 years. Is it contracting? gravitational potential energy / luminosity = 25 million years. It can be powered by nuclear energy. Therefore the sun is not on fire. Nuclear potential energy (core) / luminosity = 10 billion years. In the centre = nuclear fusion = turning hydrogen into helium. Core (modeled) energy generated by nuclear fushion. Weight of upper layers compresses lower layers. In the sun, outer layers compress the inner layers. The center of the sun is hotter due to greater friction and gravity at the center. Gravitational equilibrium: without an outward force to balance the inward pull of gravity, Gravitational contraction: provided the inital energy that heated the core as the sun was. How does nuclear fussion begin? the sun would collapse into a much smaller ball forming, contraction stopped when fusion began.