PHYS 190 Lecture Notes - Lecture 14: Bok Globule, Minimum Mass, Ecliptic
7 Mar 2018
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Competition b/w 2 forces: electrical & nuclear. Strong nuclear force - by far the most powerful force: but can only act when nuclei are very close. Tremendous heat/energy needed to get protons close enough - 10 million degrees. Mass number = number of protons + neutrons. 41h 4he + energy + 2 . Only 0. 7% of input mass is converted to energy. Sun"s mass lifetime of about 10 billion years. Pressure-temperature thermostat - example: if extra fuel could be added to centre of. Sun, causing temperature to increase slightly, that would initially cause nuclear reactions to occur faster, and release even more heat. So sun"s core would expand, cool, then return to original condition. Star"s mass determines its properties & its fate. Stars spend 90% of their lives on the main sequence. Adult star burns hydrogen into helium in the core. Over time, less fuel available in the core. Most reactions make amount of fuel available go down.
