ASTR 102 Final: Study Guide
13 Apr 2015
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Chapter 13: the milky way: size and shape. ~50 million ly: hershel: used telescope to see in various directions, concluded we are near the centre, kapteyn: long-exposure photo shows many more *s, near centre of lens-shaped system. Leavitt: studied cepheids in lmc and found period-luminosity relationship used to find distances within the mw and to external galaxies: period-luminosity: pulsation period correlated with absolute magnitude. Dust blocks much of view in visible wavelengths. Passes much better through dust far-infrared reveals dust emission from disk of mw: near-infrared reveals cool stars in disk and bulge shows much smoother appearance cooler stars spread uniformly across disk three major components: Stars and globular clusters orbit in random directions. Mixture of i and ii, but no blue o and b. Believe mw is similar to other spiral galaxies we observe. Globular clusters: old objects with low metallicities, found mostly in the bulge and halo of the.
