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Black Holes . This one’s green. I like green. . What happens after a SN?. Material remaining after a supernova is 3 times more massive than the sun or more Pressure is strong enough to collapse the star beyond the neutron-degenerate pressure. Star remnant collapses and vanishes.

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black holes

Black Holes

This one’s green.

I like green.

what happens after a sn
What happens after a SN?
  • Material remaining after a supernova is 3 times more massive than the sun or more
  • Pressure is strong enough to collapse the star beyond the neutron-degenerate pressure.
  • Star remnant collapses and vanishes.
characteristics of a black hole
Characteristics of a black hole
  • MATTER IN A BLACK HOLE LOSES ALMOST ALL OF ITS ORIGINAL CHARACTERISTICS!
  • Retains only:
    • Mass (therefore the gravity)
    • Its angular momentum

*** All other characteristics no longer exist!

  • concepts like protons, electrons, neutrons, molecules, compounds etc. no longer apply.
i have a headache
??? I have a headache.
  • Escape Speed- speed needed for an object to escape the gravity of another.
    • Bigger mass= bigger grav, then bigger ES
    • Smaller radius= bigger grav, then bigger ES
  • The escape speed for a black hole is greater than the speed of light.
  • Nothing can exceed the speed of light (except Bause when he runs towards the lunch line) SO nothing can escape a BH
singularity
Singularity
  • General relativity (Einstein) predicts that in creating a black hole, matter compresses to infinite density.
  • ALL known laws of physics are invalid.
  • Recall Relativity explains the behavior of the really massive, quantum mechanics explains the behavior of the really small (subatomic stuff). A black hole is both REALLY massive and REALLY small.
schwarzschild radius
Schwarzschild radius
  • The radius that matter (any matter, does it matter?) must be compressed for it to have an escape speed equal to the speed of light.
  • All objects have a SR
    • Earth = 1 cm or a grape
    • Jupiter = 3 cm or 3 grapes (I’m not creative)
    • Sun = 3 km
event horizon
Event Horizon
  • The location around a black hole where the escape speed EQUALS the speed of light.
  • Everything in the EH is lost forever. No information can be gathered from within.
  • Outside of the EH, everything appears to “slow”… called gravitational redshift
gravitational redshift
Gravitational Redshift
  • Speed of light is CONSTANT through constant medium.
  • In order for light to escape gravity it must work (use energy). Greater the grav, more energy.
  • SO, light will lose energy and shift towards red portion of electromagnetic spectrum (longer wavelength)
gravitational lens
Gravitational Lens
  • Gravity can bend light rays.
  • This can allow us to see objects normally too far for us to see.
  • Bause diagram.
infalling matter
Infalling Matter
  • Matter closest to the BH will be pulled greater, stretching the matter.
  • Eventually pulled apart, atom by atom.
does a black hole last forever
Does a black hole last forever?
  • Nope.
  • They can evaporate through Hawking Radiation (more in your lab).
  • Process takes a LONG time. A 5 solar mass black hole would take 1062 years to evaporate. So, black holes that have formed, still exist today.
supermassive black holes
Supermassive Black Holes
  • All elliptical and spiral galaxies seem to have one in the center. Irregular galaxies (aka dwarf galaxies) do not.
  • A black hole with the mass of millions to billions of Suns!
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