l19 - Today HW #8 due Friday 4/9 at 8am Exam 2 Extra Credit...

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ISP209s10 Lecture 19 -1- Today • HW #8 due Friday 4/9 at 8am • Exam 2 Extra Credit due Fri 4/2 at 8pm (12 extra hours) • New topic: Stars – The Sun and “Space Storms” video – Classification of Stars, what they are made of, what they “run” on – Birth and Death of Stars – some Clicker ?’s
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ISP209s10 Lecture 19 -2- New topic: Our Sun • A huge, hot ball of mostly hydrogen and helium (3% other stuff) • Power output (luminosity) 3.26E+26 W • It is 93 million miles from Earth. Intensity at the Earth is about 1000 W/m 2 . That is like ten 100 W light bulbs every square meter • The Sun is a complicated object
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ISP209s10 Lecture 19 -3- Some Sun Factoids Sunlight takes 8.3 minutes to reach earth T core = 16,000,000 K, T surface = 5800 K, T corona = 5,000,000 K Surface gravity = 27.94g Radius = 109 R earth Volume = 1,300,000 V earth Mass = 333,000 M earth 1 Rotation every 26 days Orbits the center of Milky way every 2.5E+8 years Photons in the core take 10,000 - 100,000 years to reach the surface of the sun
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ISP209s10 Lecture 19 -4- Our Sun is a complex and dynamic object Spicules Corona
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ISP209s10 Lecture 19 -5- A short diversion: “Space Storms” http://www. pbs .org/wgbh/nova/sciencenow/0304/02.html “Aurora-Borealis” or “Northern Lights” due to the interplay Of the sun’s activity and Earth’s magnetic field
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ISP209s10 Lecture 19 -6- Questions to ponder How do we know what our sun (and other stars) are made of ? How do we know the temperature? How do we know the size? • What is the energy source that makes stars “run”? • Who cares…what does it have to do with me? (hint: you are made of star stuff) • How are stars formed, how do they evolve, how do they “die”?
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ISP209s10 Lecture 19 -7- Blackbody Radiation All objects emit a spectrum of photons. A perfect black body has the spectrum shown at the left. Stars are black bodies.
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l19 - Today HW #8 due Friday 4/9 at 8am Exam 2 Extra Credit...

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