PCS 181 Lecture Notes - Lecture 4: Galaxy Zoo, Globular Cluster, Horse Length
21 Mar 2013
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A globular cluster is a spherical distribution of ~105 to 106 stars. Formed early in the life of a galaxy and contain the oldest stars known. Follow random paths through their home galaxy = do not move ~ circularly in the plane (disk) of the galaxy as most stars do. They are found above, below and within their galaxy. See handout for characteristics of each type. The color of galaxy is the sum of color contributions from its stars. Spirals: central bulge is reddish-orange from old stars there. Spiral arms are blue from the presence of hot young stars (forming from the gas and dust in the arms) Irregulars: contain largest amounts of dust/gas are the blue-est galaxies known and support the most active star birth. ***know the handout for the midterm test #1*** 30 multiple choice questions 25 conceptual and 5 math questions. Luminosity = l = total energy emitted each second.
