ASTRON 2B03 Lecture Notes - Low Frequency, Cosmic Distance Ladder, Spacetime
25 Sep 2013
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Spirals: our milky war, think, disk-like (similar to a frizbee) [2d, have spiral arms, stars are being formed today. Ellopticals: compared to a frizbee, they are 3d. Similar to a balloon: similar, as well, to a cloud of bees. Within galaxy, stars move around like bees flying about: not much rotation and star formation. Most galaxies are one or the other. Galxies don"t live in isolation -> they have nearby neighbours. They live in galaxy grouos: feel each other"s gravitational forces. Our milky way have tiny galaxies orbiting around us, as well as have other large galaxies around us (andromeda) Some live in isolation, but most common is in groups. Compact (galaxy) groups distances between galaxies are smaller than galaxies themselves. Two spirals colliding (galaxies) -> may create an ellicptical galaxy. Two ellicptical galaxies colliding will create a larger elliptical. Different in magnitude : group has like 30-50 (no rigid boundary, cluster may have like 1000 (much more)
