ASTR-1010 Lecture Notes - Lecture 13: Spiral Galaxy, White Dwarf, Tuning Fork
6 Oct 2016
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Document Summary
We study life cycles of galaxies the same way we do stars: observe many different galaxies at various stages of their lives, this is more difficult than for stars. Young galaxies are only found at very great distances. Classification of galaxies: astronomers classify galaxies into three major types. Irregular: the sizes of all three types span a wide range, from. Some spiral galaxies have a bar of stars cutting through their centers: spiral arms are attached to the ends of the bar, we call them barred spiral galaxies, the milky way is probably a barred spiral. Elliptical galaxies: only have a spheroidal component; no disk component, very little or no ism, usually appear reddish because they contain mostly red stars. Irregular galaxies: appear blue and dusty, with ism. Have more in common with the disk component of spirals: distant galaxies are more likely to be irregular. They were more common when the universe was young.
