GEOL_notes0_201

GEOL_notes0_201 - GEOL 201 FALL 2008 NOTES 0.0 Cosmology:...

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GEOL 201 FALL 2008 NOTES 0.0 Cosmology: origin of the universe and origin of matter in the universe Definitions Atom the smallest, indivisible part of an element (see below for definition of an element). Protons : positively charged particles that typically reside in the nucleus of an atom. Neutrons : particles that are slightly more massive than protons, but have no charge. They typically reside in the nucleus of an atom. Element : determined by the number of protons in an atom. Electrons : Negatively charged particles that form clouds around atomic nuclei. The mass of an electron is 1/1837 that of a proton. The diameter of an electron "cloud" can 100,000 times larger than the diameter of a nucleus. <cosmology.pdf> posting Stars: providers of radiation (including visible light) and elements Gravity and radiation are in balance. Particles are attracted to each other by gravity. This attraction is balanced by heat resulting from fusion . In fusion, nuclei of lighter elements collide and as a result nuclei of heavier elements form and energy is released . The heavier element produced is LIGHTER than the two nuclei that combined; the "lost" matter is converted to energy E=MC 2 Factoids regarding fusion in stars and the genesis of elements Great velocities are required to overcome inter-atom electromagnetic repulsion that occur during fusion. Fusion collisions collision must occur at speeds of a few hundred km/sec, which require temperatures of at least 10 million K. The source of the heat is gravitational energy released during contraction/gravitational collapse. As the number of protons in a given element increases, greater velocity is required for fusion of atoms of the given element. 1 st generation stars/relatively massive stars (> or = 8 times the mass of our Sun) : as a result of their great mass, these stars can fuse elements as heavy as iron. Elements having atomic numbers greater than H and He and less than Fe are produced by burning cycles in stars. Hydrogen burning produces an "ash" core of helium. Once the helium core becomes sufficiently
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This note was uploaded on 09/30/2008 for the course GEOL 201 taught by Professor Staff during the Spring '05 term at Cal Poly.

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GEOL_notes0_201 - GEOL 201 FALL 2008 NOTES 0.0 Cosmology:...

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