class24a - Monday Oct 27 Syllabus class notes and homeworks...

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Monday, Oct. 27 Syllabus, class notes, and homeworks are at: www.as.utexas.edu courses AST 301, Lacy Reading for this week: chapter 11 The Wednesday help session is in GRG 424 at 5:00 (for the entire semester).
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New Schedule Aug 27: Ch 1+App A The Scale of the Cosmos Sep 3: Ch 2+3 The Sky, Cycles in the Sky Sep 8: Ch 4 The Origin of Modern Astronomy Sep 15: Ch 5 Telescopes Sep 19: Exam #1, Ch 1-5 Sep 22: Ch 6 Starlight and Atoms Sep 29: Ch 7 The Sun Oct 6: Ch 8 The Family of Stars Oct 13: Ch 9 The Formation and Structure of Stars Oct 20: Ch 10 The Lives and Deaths of Stars Oct 24: Exam #2, Ch 6-10 Oct 27: Ch 11 Neutron Stars and Black Holes Nov 3: Ch 12 The Milky Way Galaxy Nov 10: Ch 15 Cosmology Nov 17: Ch 16 The Origin of the Solar System Nov 24: Ch 17 The Terrestrial Planets Dec 1: Ch 18 The Outer Solar System Dec 5: Exam #3, Ch 10-12,15-19
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Death of a Planetary Nebula After 10,000-20,000 years the gas in a planetary nebula spreads out so that it no longer is bright enough to be seen easily. The core of the red giant is left behind. Without its envelope it radiates energy away faster than it generates it by fusion. From what I’ve told you, what should happen then?
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What happens You should expect it to contract and heat up so fusion will go faster. If loss of energy made the star contract, contraction would heat it. But when a white dwarf loses energy it does not contract. Instead it cools off and fusion stops. The leftover core of the red giant is called a white dwarf. The reason it doesn’t contract and heat up is that it has an unusual form of pressure: electron degeneracy pressure, which doesn’t depend on temperature.
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Electron degeneracy pressure
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This note was uploaded on 07/13/2010 for the course AST 301 taught by Professor Harvey during the Fall '07 term at University of Texas.

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class24a - Monday Oct 27 Syllabus class notes and homeworks...

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