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Lecture

Astronomy - Session 6

5 Pages
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Department
Astronomy
Course Code
ASTA02H3
Professor
Parandis Khavari

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Description
Astronomy - Session 6  stars shine for billions of years  only a nuclear source can provide such a vast amount of energy  nuclear fusion in Sun’s core  source of energy  nuclear energy can be produced via two procedures  1. fission  2. fusion  fusion  assembles new forms of old, lighter nuclei atoms into heavier  fission is opposite to fusion  gravity  electromagnetism  weak/strong nuclear force  only operates in the nucleus  elementary particles: protons and electrons  at the beginning, it was believed that only one force existed  that one force later broke up into four  fission  breaks nucleus of heavy atoms into small nuclei  electrons hit atoms, breaks the atoms  energy is released  fusion forms heavier elements using lighter  ex. 4 Hydrogen atoms form a Helium  Q. Why are charged protons in the nucleus tightly bound when they should repelled?  A. strong nuclear force  only happens at very hot temperatures  proton changes  at 10 million degrees Kelvin  there is enough energy to give nuclear force time to bind  How much energy?  e c  Sun  unlikely that four protons (4 Hydrogen atoms) would collide to make Helium  happens one by one, not all at once   energy released in gamma-ray form  H + H 2H + e +  neutrinν:  difficult to get absorbed in anything  neutrino escapes  once produced by the Sun  escape  2% of the energy produced by the Sun  pass through anything  nothing at 10 million degrees Kelvin can remain an atom  + H e +  gamma-ray oven  e e e  proton-proton chain  e c  mass of Hydrogen atom: g  mass of the atom: g  Q. Where is the energy from the fusion?  how to relate (mas
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