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BLACK HOLES
AIM: USE STELLAR EVOLUTION TO DESCRIBE HOW
BLACK HOLES ARE FORMED
DEFINE THE EVENT HORIZON AND A SINGULARITY
Astronomy - White Dwarfs_Neutron Stars_Black Holes.pptx
THE SUN WILL BECOME A
WHITE DWARF
• In a white dwarf the atoms are getting pressed together
• Gravity compacts the matter inward
• The electrons in the atoms cannot be squeezed any more
Astronomy - White Dwarfs_Neutron Stars_Black Holes.pptx
ELECTRON DEGENERACY PRESSURE
• When all the atoms are filled with
electrons – we call it a “degenerate” gas
• The white dwarf is stable due to a
balance between inward gravitational
pressure and out electron degeneracy
pressure
CHANDRASEKAR LIMIT
• There is a limit to how massive a white
dwarf can be
• If too much mass is introduced, then gravity
will be stronger than electron degeneracy
pressure
• The result is the electrons are “ejected” from
the star
CHANDRASEKAR LIMIT
• The Chandrasekhar Limit of 1.4 solar masses, is the
theoretical maximum mass a white dwarf star can have
and still remain a white dwarf
HOW CAN WHITE DWARF STARS GAIN MASS?
WHERE DOES THE EXTRA MASS COME FROM?
BINARY STAR SYSTEMS
WHITE DWARFS CAN
STEAL MASS FROM
THEIR COMPANION
STAR
Astronomy - White Dwarfs_Neutron Stars_Black Holes.pptx
TYPE 1A SUPERNOVA
• When a white dwarf exceeds 1.4 solar
masses it explodes
• This type of supernova have a known
luminosity
• Used to calculate distances in space
WHITE DWARF STARS ARE VERY DENSE.
WHAT IS DENSER THAN A WHITE DWARF?
•Neutron stars!!!!
•And black holes!!!
NEUTRON STARS
• Like white dwarfs, they are held together by
neutron degeneracy pressure
NEUTRON STARS LIMIT
• Neutron stars also have limits
of how massive they can be
• About 3 Solar masses
NEUTRON STARS COLLAPSE TO
FORM BLACK HOLES
Astronomy - White Dwarfs_Neutron Stars_Black Holes.pptx
BLACK HOLES
• Black holes are the most massive and
most dense objects in the universe.
• It has two major characteristics
• An event horizon
• A singularity
BLACK HOLES – EVENT HORIZON
• Event Horizon - the spherical outer
boundary of a black hole loosely considered
to be its "surface."
• It is the point that the gravitational
influence of the black hole becomes so
great that not even light is fast enough to
escape it
ESCAPE VELOCITY
FOR A BLACK HOLE IS
300,000 KM/S AT THE
EVENT HORIZON
Astronomy - White Dwarfs_Neutron Stars_Black Holes.pptx
BLACK HOLE - SINGULARITY
• The singularity at the center of a
black hole is the ultimate no
man's land: a place where
matter is compressed down to
an infinitely tiny point, and all
conceptions of time and space
completely break down.

More Related Content

Astronomy - White Dwarfs_Neutron Stars_Black Holes.pptx

  • 1. BLACK HOLES AIM: USE STELLAR EVOLUTION TO DESCRIBE HOW BLACK HOLES ARE FORMED DEFINE THE EVENT HORIZON AND A SINGULARITY
  • 3. THE SUN WILL BECOME A WHITE DWARF • In a white dwarf the atoms are getting pressed together • Gravity compacts the matter inward • The electrons in the atoms cannot be squeezed any more
  • 5. ELECTRON DEGENERACY PRESSURE • When all the atoms are filled with electrons – we call it a “degenerate” gas • The white dwarf is stable due to a balance between inward gravitational pressure and out electron degeneracy pressure
  • 6. CHANDRASEKAR LIMIT • There is a limit to how massive a white dwarf can be • If too much mass is introduced, then gravity will be stronger than electron degeneracy pressure • The result is the electrons are “ejected” from the star
  • 7. CHANDRASEKAR LIMIT • The Chandrasekhar Limit of 1.4 solar masses, is the theoretical maximum mass a white dwarf star can have and still remain a white dwarf
  • 8. HOW CAN WHITE DWARF STARS GAIN MASS? WHERE DOES THE EXTRA MASS COME FROM? BINARY STAR SYSTEMS WHITE DWARFS CAN STEAL MASS FROM THEIR COMPANION STAR
  • 10. TYPE 1A SUPERNOVA • When a white dwarf exceeds 1.4 solar masses it explodes • This type of supernova have a known luminosity • Used to calculate distances in space
  • 11. WHITE DWARF STARS ARE VERY DENSE. WHAT IS DENSER THAN A WHITE DWARF? •Neutron stars!!!! •And black holes!!!
  • 12. NEUTRON STARS • Like white dwarfs, they are held together by neutron degeneracy pressure
  • 13. NEUTRON STARS LIMIT • Neutron stars also have limits of how massive they can be • About 3 Solar masses
  • 14. NEUTRON STARS COLLAPSE TO FORM BLACK HOLES
  • 16. BLACK HOLES • Black holes are the most massive and most dense objects in the universe. • It has two major characteristics • An event horizon • A singularity
  • 17. BLACK HOLES – EVENT HORIZON • Event Horizon - the spherical outer boundary of a black hole loosely considered to be its "surface." • It is the point that the gravitational influence of the black hole becomes so great that not even light is fast enough to escape it
  • 18. ESCAPE VELOCITY FOR A BLACK HOLE IS 300,000 KM/S AT THE EVENT HORIZON
  • 20. BLACK HOLE - SINGULARITY • The singularity at the center of a black hole is the ultimate no man's land: a place where matter is compressed down to an infinitely tiny point, and all conceptions of time and space completely break down.

Editor's Notes

  1. By R.N. Bailey - Own work, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=59672008