ASTR 101 Lecture Notes - Lecture 17: Molecular Cloud, Planetary Nebula, Galaxy Rotation Curve
13 Dec 2016
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How do we know about the milky way? (review) Milky way looks like a disk with a bulge in the middle. Variable stars - using them to calibrate distance using spectroscopic parallax. Interstellar medium - very low density clouds extended over 100s of lightyears; also very very cold so they do not emit visible wavelength light; however do emit tons of infrared energy. The ism - birthplace of stars - by looking at the youngest stars we can track down where stars are formed. We can find places where stars appear to be currently forming - inside dark globules of dark and cold matter. Massive stars do not live very long; non-massive stars live longer, but burn cooler. Think of a massive star as a ferrari. Think of a small star as a prius. A piece of molecular cloud becomes dense and stars to collapse. Density grows in center and material continues to fall in under gravity.
