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 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 Chinese Chinese, European, Anasazi? Tycho’s Star Kepler’s Star 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 tons/(150 x 10 6 km) 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?
Protoplanetary Disks in Orion