AST201H1 Lecture Notes - Lecture 14: Hypothesis, Baryon, Bullet Cluster

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST201H1
• Professor: Michael Reid

Document Summary

Recall: when fritz zwicky used the motions of galaxies in clusters to measure their masses, he got an answer much higher than the amount of mass that was visible. Kepler"s first law: orbits are ellipses with the center of mass of the system at one focus (adapted for objects beyond the solar system) Kepler s third law; stars farther away from the center of the galaxy should rotate slower than those closer to the center. Keplerian rotation curve- describes objects moving in accord with kepler"s third law. You get a keplerian rotation curve when lots of low-mass objects orbit one really massive central one. Orbital speeds in our solar system decrease with distance from the sun bc most of the mass in our solar system is concentrated in the sun [keplerian rotation curve for the planets in our solar system] Vera rubin measured the rotation curves of galaxies, including the parts way beyond the luminous part.