ASTR 114 Lecture Notes - Lecture 18: Hubble Deep Field, Caroline Herschel, Globular Cluster
10 Jan 2020
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Lecture 20: globular cluster - up to a million or more stars in a dense ball bound together by gravity, cool. Open cluster- a few thousand loosely packed stars, hot. Knowing a star cluster"s distance, we can determine the luminosity of each type of star within it. the main sequence turnoff point of a cluster tells us its age. The amount of luminosity passing through each sphere is the same. Area of sphere: 4 (radius)2 divide luminosity by area to get brightness. White-dwarf supernovae can also be used as standard candles. conservation of angular momentum creates an accretion disk. Lecture 21: one of the first attempts to measure the milky way was done by william and caroline herschel using visible stars ( blocked by gas and dust). Before hubble, some scientists argued that "spiral nebulae" were entire galaxies like our milky way, while others maintained they were smaller collections of stars within the.
