ASTR 1102 002 2008 Fall Semester Joel E Tohline Alumni Professor Office 247 Nicholson Hall Slides from Lecture20 Chapter 23 Our Galaxy and Chapter 24 Galaxies Schematic Illustration of Our Milky Way Galaxy Stellar Populations Pop I Pop II Location Galaxy s disk Throughout Galaxy s halo Kinematics Circular orbits in the disk Significant motion out of the disk Metallicity High Low Stellar Populations Pop I Pop II Location Galaxy s disk Throughout Galaxy s halo Kinematics Circular orbits in the disk Significant motion out of the disk Metallicity High Low Age Young Old Stellar Populations Pop I Pop II Location Galaxy s disk Throughout Galaxy s halo Kinematics Circular orbits in the disk Significant motion out of the disk Metallicity High Low Age Young Old What about Pop III Stellar Populations We are only able to study and delineate well these different stellar populations in our own MW Galaxy The presumption is that all other galaxies contain these same populations of stars although the fraction of stars belonging to Pop I vs Pop II varies from galaxy to galaxy Center of Our Milky Way Galaxy Evidence for a Massive Black Hole at the Center of Our Milky Way Galaxy Center of Milky Way Galaxy More about Galaxies Individual Stars early in the semester Location in Space Coordinate angular position on the sky Distance from Earth Motion through Space Motion across the sky proper motion Motion toward away from us radial velocity Intrinsic properties Brightness luminosity magnitude Color surface temperature Mass Age now let s discuss Individual Galaxies Location in Space Coordinate angular position on the sky Distance from Earth Motion through Space Motion across the sky proper motion Motion toward away from us radial velocity Intrinsic properties Brightness luminosity magnitude Color surface temperature Mass Age Individual Galaxies Location in Space Coordinate angular position on the sky Individual Galaxies Location in Space Coordinate angular position on the sky Distance from Earth Distance Ladder Individual Galaxies Location in Space Coordinate angular position on the sky Distance from Earth Motion through Space Motion across the sky proper motion None observable Motion toward away from us radial velocity Extremely revealing discovery made by Slipher Hubble Humason Individual Galaxies Location in Space Coordinate angular position on the sky Distance from Earth Motion through Space Motion across the sky proper motion None observable Motion toward away from us radial velocity Extremely revealing discovery made by Slipher Hubble Humason Individual Galaxies Location in Space Coordinate angular position on the sky Distance from Earth Motion through Space Motion across the sky proper motion None observable Motion toward away from us radial velocity Extremely revealing discovery made by Slipher Hubble Humason Individual Galaxies Location in Space Coordinate angular position on the sky Distance from Earth Motion through Space Motion across the sky proper motion None observable Motion toward away from us radial velocity Extremely revealing discovery made by Slipher Hubble Humason Individual Galaxies Location in Space Coordinate angular position on the sky Distance from Earth Motion through Space Motion across the sky proper motion None observable Motion toward away from us radial velocity Extremely revealing discovery made by Slipher Hubble Humason