27- ) - ASTR100Lg Lasttime Debris:Icy&Rocky...

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ASTR 100Lg Last time Read section 14:10   Plutinos o Pp. 395-396   Meteor showers The Sun (Part III) In Lectures: Data   posing questions o Idea: Sun considered as an example of a star Universal issues:  o Interior structure o How does it work? Basic Data for Sun M Sun  = 1.99x10 30 kg   333,000 M Earth   1000 M Jupiter R Sun  = 696,000 km   109 R Earth    10 R Jupiter Average density = 1.4 g/cm 3    Jovian density Composition of Sun
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Book: 74% Hydrogen, 25% Helium, 1% Other o Misleading: this is only the upper layers Overall: 71% Hydrogen, 27% Helium, 2% Other o Looks like a vast Jovian object Why aren’t Jovians stars? o How big has a Jovian got to be before becoming a star? Answer: M Jovian  > 8% M Sun    star Basic Facts Sun is divided into three different zones: o Core   2x10 5  km o Radiation Zone   5x10 5  km o Convection Zone   7x10 km Temperature drops as you move outwards o Photosphere, T=5800K The “crust” of the Sun Core: o Energy is being generated Radiation Zone: o Energy is being transferred outward by Radiation
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Convection Zone: o Energy is transferred outward by Convection Photosphere: o Outermost layer from which light finally breaks free Core T Core  = 15.6x10 6 K, density in core = 160 g/cm 3 Helioseismology Sun vibrates/oscillates   measure with high precision o Similar to the study of earthquakes Combinations of vibrations (similar to that of musical instruments) allow of the  Interior structures of the Sun to be recreated/imagined o Recall: resonance Natural frequencies of vibration depend upon temperature and density  of the gas “Resonances of the Sun” o From this, we can establish density and temp. in interior of Sun What is the source of Energy of Sun? Issue   1850 Quantify the problem: Sunlight reaching Earth deposits 1400 Watt/m 2 o Total energy output of Sun must be equal to…
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1400 Watts x the area of the sphere outlined by Earth’s orbit 1400 W x 4 π  x (1.496x10 11 m) 2 4x10 26  Watts Wattage of Sun has been known for 200-300 years o 1850   industrial revolution driven by control and management of “chemical energy” (Engines) Victorian engineers understood this very well Suggestion:  Could it be chemical energy that powers the Sun? o
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This note was uploaded on 11/27/2009 for the course ASTR 50800 at USC.

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27- ) - ASTR100Lg Lasttime Debris:Icy&Rocky...

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