Lecture 19

Lecture 19 - Today (Weds.) in Astro 3 Finish Chapter 11...

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Today (Weds.) in Today (Weds.) in Astro Astro 3 3 z Finish Chapter 11 “The Interstellar Medium”, start Chapter 12 “Stellar Evolution” z Cell phones off now, please z Midterm #2 on Friday: Í Just like midterm #1 in structure, but concentrating on the new material Í Relevant lectures (chapters 6-11) are on the class web site
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Summary of Chapter 11 (thus far) Interstellar medium is made of gas and dust Emission nebulae are hot, glowing gas associated with the formation of large O and B stars Dark dust clouds, especially molecular clouds, are very cold. They may seed the beginnings of star formation. Dark clouds can be studied using the 21-cm emission line of molecular hydrogen. Star formation begins with huge fragmenting, collapsing cloud of gas and dust, with 100’s or 1000’s of solar masses
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11.4 Formation of Stars Like the Sun Star formation starts when part of a large, cold dust cloud begins to contract under its own gravitational force As it collapses , gravitational energy Æ random kinetic energy, and the center becomes hotter and hotter If enough material collapses, temperature will eventually rise enough so that nuclear fusion begins in the core.
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11.4 Formation of Stars Like the Sun The Orion Nebula contains interstellar clouds in the process of contracting, as well as protostars.
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11.4 Formation of Stars Like the Sun Stage 4 : The core of the cloud is now a protostar , and makes its first appearance on the H-R diagram :
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11.4 Formation of Stars Like the Sun Planetary formation has begun, but the protostar is still not completely in equilibrium all heating comes from the gravitational collapse .
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11.4 Formation of Stars Like the Sun The last stages
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This note was uploaded on 04/16/2008 for the course ASTR 3 taught by Professor Hauser during the Fall '07 term at UCLA.

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Lecture 19 - Today (Weds.) in Astro 3 Finish Chapter 11...

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