Lec18 - Class Assignments Extra Credit/Honors "Letter of...

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Class Assignments • Extra Credit/Honors – "Letter of Intent" today 5 p.m. . – Warning on plagarism. .. • For Friday: – Do Online Exercise 10 ("H-R Diagram" tutorial)
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Upcoming Events Greg Laughlin will speak on “The Search forAnother Earth,” for this year’s “ Vernon Lecture” on Wednesday, Oct. 19, at 7:30 p.m., at the University of Delaware’s Clayton Hall Conference Center. Register for the event, which is free and open to the public, at this website:http://darc.physics.udel.edu/wet/vernon/ vernon.html Those who attend will receive back 10% of the points lost in midterm #1. Be sure to sign the attendance sheet I will bring to the lecture.
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Proton-Proton Chain IN: 6 H, (2 e - ) OUT: He, 2 H, 2 ν e , 4 γ Effectively 4 H nuclei are converted into 1 He nucleus and energy is released.
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Why does the Sun Shine ? But…. mass of He = 99.3% of 4 x mass of H where did the .007 (4 m H ) go? Into energy!!! E = mc 2
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• Sun’s luminosity is stable over short-term. • However, as more Hydrogen fuses into Helium: • 4H -> He, # of particles in Sun’s core decreases with time • Core contracts, causing it to heat up • Fusion rate increases to balance higher gravity • Sun’s luminosity gradually increases with time • Models => 30% increase in luminosity since Sun formed 4.6 billion years ago. • from initial 2.9 x 10
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This note was uploaded on 02/01/2012 for the course PHYS 133 taught by Professor Staff during the Fall '08 term at University of Delaware.

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Lec18 - Class Assignments Extra Credit/Honors "Letter of...

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