Astronomy 1021 Study Guide - Final Guide: Electromagnetic Spectrum, Massive Compact Halo Object, Accelerating Expansion Of The Universe
9 Jul 2014
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Document Summary
Stars are born from and return most of their mass (containing heavier elements) to the interstellar medium so new stars can form. We live in the local bubble (a hot bubble (ionized gas) - means sn"s must have gone off near us a few million years ago) Can trace molecular clouds through radio emission of the co molecule (co line emission) Gas clouds compress when they move into spiral arms and start star formation. Stars closer to galactic center orbit faster. More mass equals faster orbit in stars. Speed declines as radius increases (kepler"s law) Finding mass from velocity using doppler shift. Stars with many absorption lines from heavier elements (high metal stars) = population i stars (found in disk and spiral arms) [young stars] Stars with few absorption line, and those almost exclusively from h and he (low metal stars) = population ii stars (found in halo, globular clusters or central bulge) [old stars]
