AST201H1 Chapter Notes - Chapter 23.1 - 23.4: Orbital Speed, Galaxy Formation And Evolution, Weak Interaction

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST201H1
• Professor: Bryan Gaensler

Document Summary

23. 1 - 23. 4: dark matter, dark energy, and the fate of the. Do not know what universe is made of. What do we mean by dark matter and dark energy. What is the evidence for dark matter in galaxies. Most of mass in our solar system is concentrated in the sun, so farther planets orbit slow. Most of mass in milky way galaxy must not be concentrated at the centre, since. Most mass is distributed through spherical halo, detected little radiation from this mass --> dark matter. If total mass is larger than mass attributed to stars, then excess mass must be dark matter. Measure luminosity by measuring apparent brightness / distance / inverse square law. Measure mass by measuring orbital speeds of stars or gas clouds. Do not have large well-organized disks in which we can easily measure how the orbital speeds of stars depend on distance.