PCS 181 Lecture Notes - Lecture 1: Large Magellanic Cloud, Proper Motion, Minute And Second Of Arc
23 Apr 2016
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A plot of stellar luminosity (or magnitude) vs surface temperature or spectral type. Spectral classes: o, b, a, f, g, k, m (hottest to coldest, highest to lowest mass) Pneumonic: oh, be a fine girl/guy, kiss me. Hr diagram has distinct regions: giants, main sequence, white dwarfs. This method enables us to determine distance to farther stars. Find distance (in pc and in ly) to a main sequence star with apparent magnitude of -1. 1 and a surface temperature of 10 000 k. 5log d=m-m+5 log d= d= d= d= d=2. 4pc=7. 8 ly. A cepheid variable star grows larger and brightens. Entire cycle occurs over a timespan of days. Henrietta leavitt produced a plot of period vs magnitude (m) Cepheids can be used as farther distance indicators to other galaxies. A cepheid in another galaxy has an avg apparent magnitude of 15 and a period of 10 days. What is distance (in pc and in ly) to.
