Energy Sources in Stars (§10.3)
Energy Sources in Stars (§10.3)
Energy Sources in Stars (§10.3)
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<strong>Energy</strong> <strong>Sources</strong> <strong>in</strong> <strong>Stars</strong><strong>Energy</strong> Source #3:Nuclear <strong>Energy</strong>Fission?Z = 0.02 (2% Sun consists of heavy elements).Fissionable isotopes like 235 U are rare (isotopes are nucleiiwith the same # protons but different # neutrons)Fusion?e.g. 4 protons get converted <strong>in</strong>to 2p + 2n i.e. i4H → 1 4 HeH is very abundant <strong>in</strong> the Sun (X = 0.73)4 H nuclei: mass = 4 x m p = 6.693 x 10 -27 kg1 4 He nucleus: mass = 6.645 x 10 -27 kg (b<strong>in</strong>d<strong>in</strong>g energy <strong>in</strong>cluded)Difference is 0.048 x 10 -27 kg = 0.7% of orig<strong>in</strong>al massWhere does this mass go?
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