lecture12

lecture12 - Astronomy 3: The Nature of the Universe...

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Astronomy 3: The Nature of the Universe Professor Alice Shapley Lecture 12: The Sun Measurements of Stars (NGC 1499 Image credit: Markus Noller, Deep Sky Images)
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Logistics Quiz #6: due Monday, May 16th, 10 pm. Available at CCLE website https://ccle.ucla.edu/course/view/11S-ASTR3-2
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Logistics Midterm #2 , this Thursday, May 12 th , in class. The midterm will take place in the regular lecture hall, Math Sciences 4000A -- i.e., this room. Most important : bring a photo ID and a #2 (i.e. normal) pencil. Recommended: bring a calculator (though you may not need it). I will provide scantrons. Review session : TONIGHT, Tuesday, May 10 th , 6-8 pm, also in Math Sciences 4000A.
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Logistics Exam will have a mixture of multiple choice, matching, and true/ false. Exam will emphasize material on The Solar System, Terrestrial and Jovian Planets, Extrasolar Planets, and the Sun. This material corresponds to lectures 6-11 and first part of 12. The relevant reading from the textbook is: Chapters 7, 8, 9, 10, 11, 13, 14. If relevant to these topics, I will assume you remember material from the first part of the course (e.g., Doppler shift, gravitational force, meaning of temperature, conservation of energy). A few questions will be based on Labs.
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Review from Last Time Extrasolar planets: – Current events: Kepler mission has found rocky planets, and lots of multiple-planet systems. – Extrasolar planet statistics (“hot Jupiters” – i.e. most planets are significantly more massive than Earth, and quite close in to parent star, with majority within 1 AU). The Sun.
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Our Goals for Learning: What are the basic properties and structure of the Sun? Why does the Sun shine? What’s the nature of solar “activity”?
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Layers of the Sun Core 1.5 x 10 7 K 0.20 R sun Radiation Zone > 2 x 10 6 K (0.713-0.20) R sun Convection Zone < 2 x 10 6 K (1.0-0.713) R sun Photosphere 5.8 x 10 3 K 400 km thick Chromosphere 1– 5 x 10 4 K 2,500 km thick Corona 2 x 10 6 K 600,000 km thick Solar Wind > 10 6 K beyond orbit of Pluto Temperature Thickness
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Methods of Energy Transport Radiation Zone energy travels as photons of light, which continually collide with particles always changing direction ( random walk ), photons can change wavelengths this is called radiative diffusion This is a slow process! It takes about few 10 5 years for energy to travel from the core to the surface.
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Convection zone photons arriving at bottom of convection zone are absorbed instead of scattered by matter the bottom of the zone is heated … hot gas rises to the top cooler gas sinks to the bottom…just like when you boil a pot of water! energy is brought to the surface via bulk motions of matter (
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This note was uploaded on 10/28/2011 for the course ASTR 3 taught by Professor Hauser during the Spring '07 term at UCLA.

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lecture12 - Astronomy 3: The Nature of the Universe...

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