ASTA02H3 Lecture Notes - Orbital Speed, Spiral Galaxy, Brown Dwarf
Document Summary
Milky way (galaxy), dark matter, black hole at the center of the galaxy. Galileo confirmed that the white band (the milky way) was made of stars. Determined the shape of the milky way through star distribution. Not a sphere because the stars were not uniformly distributed. Thought that the sun was close to the center of the milky way. Thought that the sun was 600 pc away from the center. Thought that the shape of the milky way was a disk. Obstructs view, esp. towards the center of the galaxy. Emission can be seen from very far away. Galaxy is probed in 21cm lines of hydrogen. Known that globular clusters were not uniformly spread. Noticed stars regularly changing brightness located at approx. same distance. Relationship between intrinsic brightness and pulsation period the brighter a star, the larger the period. Identified stars called cepheid variables after which was the first one of these to be identified.
