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The Death Of a Star. Ask not for whom the bell tolls, it tolls for thee. How do we “know” stars die?. ____________ reveal different types of stars. How did they get there? Physics tells us how stars work. __________ depends on mass (L:M 4 ) (Gas)
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The Death Of a Star Ask not for whom the bell tolls, it tolls for thee
How do we “know” stars die? • ____________ reveal different types of stars. • How did they get there? • Physics tells us how stars work. • __________ depends on mass (L:M4) (Gas) • Fusion principles (4 H 1 He) tell us the rate stars use energy. (kinda like MPG on a car.) • Stars will run out of ___. (the dial goes to “E”)
Every star fights a “________”. • _______ force pulling the star together. • Fusion “_____” pushing the star apart. • Most stars find a balance. • Some stars are never balanced: • Cephids pulse as they growlarger and smaller. Gravity Fusion
A star’s fate is chosen at birth • The outcome of the battle is determined by ______ and _______ means Mass
Small Stars • Small stars last longer (don’t consume fuel as quickly) • ____________on HR diagrams. • “Burn” ________ for most of their lifetime.
Red Giants • As star runs out of hydrogen, the core _____ • Gravity starts to “win” --> _______ in core. • Increased “pressure” starts ________ fusion • 150 Million K • Carbon & Oxygen Products • ________ temperature makes outer part of star _________ yet…. • Expanded surface is actually “_______” so appears _____
Red Giants • Stars less than 1.4 Solar Masses • Gravity is _______ • Outer layers eventually “puff off” - not enough gravity • Planetary ________ forms from gas • ____________ remains
White Dwarfs • Carbon/Oxygen • Matter is ___________ • One teaspoon = a pickup truck • Electron/quantum pressures balance gravity • Very Hot : 30,000K to 200,000 K • Slowly Cool to Black Dwarfs • So slow, none exist yet. • Except this guy
Red Supergiants • Stars more than 1.4 Solar Masses • Gravitational Core Energy Reaches ___ Million K • Carbon turns to _______________ • With enough mass, even heavier elements fused • At each step, less and less energy yielded --> shorter duration • Star keeps getting ________! • _______ is the end of the road….
Review Mass • ______ determines the fate of a star. • The two forces acting on a star are ____ and _____ • When a star reaches the end of its life it begins to fuse ______ and it ______. • When fusion stops a typical star will produce a __ and become a ______ _____. • Even the largest stars can’t fuse elements heavier than _____. gravity fusion helium swells planetary nebula white dwarf iron
The party is over… • Once _____ is in the core, outwards pressure ceases • Core ________ at 1/4 the speed of light & takes about 1/10 of a second • Collapse of the core to about 100 km across • Outer layers “bounce” of the solid core • Releases 100x the energy of our sun produces in it’s lifetime -- in 1/10 of a second!!!
A supernova • Note the before / after differences • 1987A
After the party… • Lot’s of _________ hanging out during this explosion • Neutrons “_________” with lighter elements making heavy elements: • Calcium, Gold, Zinc, Uranium, etc… • Forget Hollywood ….. We are all stars!!!
Aftermath: • After a supernova explosion you can wind up several possibilities • Nebula & Neutron Star • Nebula & Pulsar • __________
Nebula • ________ of material left from the explosion • The “Primordial Goo” for new stars, planets, & people!
Supernova 1987 • Very complicated structure • Nearby star affecting the cloud
Neutron star • Forms if the remaining core is between 1.4 and 3 times the ____________ • All this mass in the size of _________! • One teaspoon > The Sears Tower • All available space in the atom (which is 99.9999% space) is removed.
Pulsar • Neutron star that ______. • Spinning magnetic field channels radiating energy into ______. • If this beam isn’t always pointing at us - it _______ like a lighthouse. • First Pulsar was mistaken as ________ communication
Black Holes • Remaining Core is more than 3x the sun. • Gravity overcomes ___________, neutrons vanish • Matter in the core overlaps : a singularity • Gravity prevents ______ from ________.--> Black Hole • Closest light can get without being trapped: “______________” • 3 S.M star = 55km E.H. (Chicago?) • Earth as a black hole? Compress it into a marble!
Finding Black Holes • May pull matter off a nearby star - Accretion Disk X-Rays • Immense mass in the center of galaxies
A trip to a black hole • Pretty Short • Difference in gravity between your head and feet literally pull you apart. • Once you hit the E.H. you aren’t coming back. • Everything you are is crushed into a single point - you no ____________ • No one would see you enter the Black Hole because time stands still at the edge.
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