ASTR 1P02 Lecture Notes - Lecture 2: Main Sequence
12 Mar 2016
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Document Summary
Stars are formed in the giant molecular clouds (gmc) Giant: diameter ranges from 15ly to 600ly. Molecular: they are dense; the dust blocks the starlight of the surroundings stars keeping the interior of the cloud cool. The low temperature makes it possible for hydrogen atoms to bind into the molecules h2. The material in gmc is not distributed uniformly- there are clumps of higher density within it. These clumps form likely because of an explosion from a nearby supernova, which produces a shockwave which produces clumps as it passes through the gmc. Some dense clumps start collapsing under their own gravity and they heat up in the process (gravitaional energy is converted into thermal energy) If the clump has enough mass so that the temperature in the core of the proto star reaches 10 million degrees k, the fusion of hydrogen into helium will start and the proto star becomes a main sequence star.
