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Life Cycles of Stars. The Hertzsprung-Russell Diagram. How Stars Form. Collapsing gas and dust cloud Protostar - mostly infrared. Main Sequence Stars. Brown Dwarf Red Dwarf Normal Star. All Objects Exist Because of a Balance Between Gravity and Some Other Force.
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How Stars Form • Collapsing gas and dust cloud • Protostar - mostly infrared
Main Sequence Stars • Brown Dwarf • Red Dwarf • Normal Star
All Objects Exist Because of a Balance Between Gravity and Some Other Force • People, Planets-Interatomic Forces • Normal Stars-Radiation • White Dwarfs-Electron Repulsion • Neutron Stars-Nuclear Forces • Black Holes-No Known Force
How Stars Die • Main Sequence Stars Brighten With Age • The More Massive a Star, the Faster it Uses Fuel • Giant Phase • White Dwarf • Supernova • Neutron Star - Pulsar • Black Hole
Historical Supernovae • 1006 - Chinese • 1054 - Chinese, European, Anasazi? • 1572 - Tycho’s Star • 1604 - Kepler’s Star • 1987 - Small Magellanic Cloud (170,000 l.y.)
Life (Briefly!) Near a Supernova • Sun’s Energy Output = 77 billion megatons/second • Let’s relate that to human scales. What would that be at one kilometer distance? • 77 x 1015 tons/(150 x 106km)2 = 3 tons • Picture a truckload of explosives a km away giving off a one-second burst of heat and light to rival the Sun
Now Assume the Sun Goes Supernova • Brightens by 100 billion times • Our 3 tons of explosive becomes 300,000 megatons • Equivalent to entire Earth’s nuclear arsenal going off one km away - every second • This energy output would last for days
Planetary Systems • Protoplanetary Disks • Accretion of Planets • Expulsion and Migration of Planets • About 30 extrasolar planets known • Our Solar System may be unusual?