Basic overview of what happens when stars die. This presentation covers white dwarfs, electron degeneracy pressure, neutron stars, neutron degeneracy pressure, black holes, event horizons and singularities

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.