AST-0009 Lecture Notes - Lecture 7: Human Eye, Binoculars
12 Mar 2016
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Document Summary
Stars are classiied by their spectra as o, b, a, f, g, k, m spectral types (oh be a fine girl kiss me) Very hot stars" electrons have been stripped of from atoms so absorption lines are faint, if exist at all. Cooler stars have stronger absorption lines because there are more hydrogen atoms that have electrons that can move to higher energy levels. For thousands of nearby stars we can ind: total luminosity, temperature (color or spectral type, size (radius, distance. H-r diagram: graph of luminosity (absolute magnitude) versus temperature (spectral class, main sequence. Goes from top left (hot and bright) to bottom right (cool and dim) 90% of stars are in main sequence stage of their lives. Really big, not very hot, but very bright. Betelgeuse: 3500k 100,000x more luminous than the sun; radius must be 1000x that of sun. Found in upper right section of h-r diagram: white dwarfs. Very small, very hot, but not very bright.
