Lecture 19

Lecture 19 - ASTR100Lecture19 LastTime: Meteorsetc....

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ASTR 100 Lecture 19 24/03/2009 13:01:00 Last Time:     Meteors etc. Read pg 395-396  Meteor showers/meteor storms Part II—Stars     Sun: An example of a star  Lectures:  Inner working/interior structure  Universal aspects of sun/stars Homework: Exterior/surface structure  Starting point: DATA  Mass of the sun is 1.99 x 10 30 kg (330,000 times the mass of the earth) (1,000  times the mass of Jupiter)  Radius of photosphere: 696,000 km roughly 109 times the radius of Earth 10  times the radius of Jupiter Photosphere : The surface from which light is emitted or leaves the sun (slightly  fuzzy but not that fuzzy) Where the light comes from  Average density~ 1.4 g/cm 3 (Water 1 g/cm 3) 
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Composition: 75% Hydrogen, 25% Helium, + 1% other at phtotosphere (in book) Believe 71% 27% 2% overall Vast “Jovian” object Why aren’t Jovians stars? What makes Jovian objects “burn”?  Sun spots  solar output varies (more intense) surface of photosphere is 5800K  lower temperature by about 1,000K  How do we know this?     Core Density: 160 g/cm 3 Core Temp: 15.6 x 10 6 K Photosphere: T = 5800K Composition: 74% H, 25% He, 1% other Primary data: Helioseismology for interior structure The sun vibrates and the gas on the sun’s surface oscillates  Resonances of natural vibrations depend on interior structure  Reconstruct the sun from it’s natural vibrations  Like reconstruct a violin from the sound it makes USC: Helioseismology group 
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What is the source of Sun’s energy     Victorian ear/ Europe ~ 1800 onwards (1850)  Industrial Revolution:      Controlling/using energy 
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Lecture 19 - ASTR100Lecture19 LastTime: Meteorsetc....

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