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Exam 2 Notes (Ch 14-18) (98% on the test)

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Louisiana State University
ASTR 1102

Chapter 14Our StarTwo kinds of balances keep its size and energy output stableGravitational EquilibriumBetween the outward push of internal gas pressure and the inward pull of gravityEnergy BalanceBetween the rate at which fusion releases energy in the Suns core and the rate at which the Suns surface radiates this energy into spaceSuns StructureSpectroscopy tells us that the Sun is made almost entirely of Hydrogen and HeliumFrom the Suns angular size and distance we determine its radius is just under 700000 kilometers more than 100 times the radius of EarthMeasure the Suns mass using Newtons version of Keplers third law30 About 2 x 10kg 300000 times the mass of EarthCan observe the Suns rotation rate by tracking the motion of sunspots or by measuring Doppler shifts on opposite sides of the SunThe entire Sun does not rotate at the same rateSolar equator completes one rotation in 25 daysIncreases with latitude to about 30 days near the solar polesRadius R696000 km about 109 times the radius Sunof Earth30Mass M2 x 10kg about 300000 times the mass Sunof Earth26Luminosity L38 x 10 wattsSunComposition by percentage of Mass70 Hydrogen 28 Helium 2 heavier elementsRotation Rate25 days equator to 30 days polesSurface Temperature5800 K average 4000 K sunspotsCore Temperature15 Million K05 arcsec20 parsecs652 light yearsSuns AtmosphereSolar Windthe stream of charged particles continually blown outward in all directions fromthe SunHelps shape the magnetospheres of planets and blows back the material that forms plasma tails of cometsCoronathe outermost layer of this atmosphere that extends several million kilometers above the visible surface of the SunHigh temperature of 1 million KRegion emits most of the Suns X raysVery low densityChromospherethe middle layer of the solar atmosphereSudden drop in temperature to 10000 KRegion emits most of the Suns ultraviolet lightPhotospherethe lowest layer which is the visible surface of the SunTemperature just under 6000 KConsists of gas far less dense than Earths atmosphere Where we find sunspotsSuns InteriorConvection Zonewhere energy generated in the solar core travels upwardConvectionthe rising of hot gas and falling of cool gasRadiation Zonewhere energy moves outward primarily in the form of photons of lightCorewhere nuclear fusion transforms Hydrogen into HeliumNuclear Fusionmakes energy by combining or fusing two or more small nuclei into a larger oneNeutrinoa subatomic particle with a very tiny mass
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