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The Death Of a Star

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  1. The Death Of a Star Ask not for whom the bell tolls, it tolls for thee

  2. 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”)

  3. 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

  4. Cepheus

  5. A star’s fate is chosen at birth • The outcome of the battle is determined by ______ and _______ means Mass

  6. Three paths

  7. Small Stars • Small stars last longer (don’t consume fuel as quickly) • ____________on HR diagrams. • “Burn” ________ for most of their lifetime.

  8. 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 _____

  9. Red Giants • Stars less than 1.4 Solar Masses • Gravity is _______ • Outer layers eventually “puff off” - not enough gravity • Planetary ________ forms from gas • ____________ remains

  10. If it’s a cloud, why does it look like a ring?

  11. Cat’s Eye: Another Planetary Nebula

  12. 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 

  13. White Dwarfs

  14. 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….

  15. The most famous S-G

  16. Fusion Layers in a Supergiant

  17. Why Stop at Iron??

  18. 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

  19. 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!!!

  20. A supernova • Note the before / after differences • 1987A

  21. 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!!!

  22. Aftermath: • After a supernova explosion you can wind up several possibilities • Nebula & Neutron Star • Nebula & Pulsar • __________

  23. Nebula • ________ of material left from the explosion • The “Primordial Goo” for new stars, planets, & people!

  24. Supernova 1987 • Very complicated structure • Nearby star affecting the cloud

  25. Our new neighbors?

  26. 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.

  27. Neutron Star

  28. 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

  29. A Pulsar

  30. 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!

  31. Finding Black Holes • May pull matter off a nearby star - Accretion Disk X-Rays • Immense mass in the center of galaxies

  32. 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.

  33. Black Holes - Expert Testimony Black Holes –More Expert Testimony