Transcript What is a Black Hole???

Birth Place of Stars:
Dark and cold inter-stellar clouds
These clouds are made of more hydrogen than
helium.
These clouds have very small amount of
heavier elements.
Beginning;
Shock waves or any other trigger may cause
contractions to begin
Gravity squeezes the particles in the nebula,
pulling every particle towards the center.
As the process continues, gravitational energy
is converted to thermal energy
Protostar
The Initial contraction period may last for a
million year.
• The temperature of this body rises slowly
until it is hot enough to radiate energy from
its surface in the form of red wavelengths.
• This large red object in the center is called
the protostar.
Protostar to a Star
During protostar stage, gravitational
contraction continues at a rapid pace.
This causes the center to heat more
intensely than the outer layers.
When the core of a protostar reaches 10
million K, pressure within is so great that
nuclear fusion of hydrogen begins.
A Star is born.
Star
• Heat from the hydrogen fusion causes the
increase in outward pressure.
• This pressure is balanced by gravity.
• This stage of the star is called the stable
state or main sequence star stage.
• Star spends most of its life in this stage.
• As long as hydrogen is available to be fused
the star will remain in that stable state.
• Beginning of the End:
– Stars begin to die when they run out of
hydrogen
• Gravity begins to take over
– Star begins to shrink; outer core of hydrogen
begins to fuse
• Star gets bigger
• Death of Stars:
– What stars end up as depend on mass
– Low and Medium mass stars
• Planetary nebula --------- white dwarf
– High mass stars
• Supernova --------- neutron star or black hole
• Death of Stars: Low and Medium Mass
Main Sequence Star
Red Giant
Planetary Nebula
White Dwarf
• Death of Stars: High Mass
Main Sequence Star
Red Super Giant
Supernova
Neutron Star
Black Hole
• High Mass Stars:
– Mass greater than 8x our sun
• Create high mass elements such as iron
– Neutron Star
• Formed if remaining star < 3x sun’s mass
– Black Holes
• Formed if remaining star > 3x sun’s mass
• What is a Black Hole???
Black
Holes Info
Sheetthat not even
– An object
so massive
and dense
light can escape its gravity
– The end result from a supernova of a star that
has a mass greater than 3x the sun
• As fusion begins to slow down, the core of
the sun will contract
• Temperature in the core will rise
• The outer layers of the sun will expand,
consuming in the inner planets
• Sun will become a Red Giant
– Core of the sun will begin to fuse helium into
larger elements such as carbon and oxygen
– Continuing over the next 100 million years…
• Core will become entirely carbon and oxygen
• Core will contract
• Outer layers will expand
– Outer layers will form a planetary nebula
• Core of sun will become a white dwarf
Death of a Star
• All stars run out of hydrogen and collapse
due to gravity.
• More massive stars burn their fuel quickly
and end their lives as supernova.
• Low mass stars do not reach the
temperatures to start fusion, so they will
remain red hot for billions of years.
• Low mass stars end as white dwarfs
Death of Sun An Average Star
• When fusion of lighter elements is not possible, outward
pressure is reduced.
• The core starts to contract, this cause the outer layers to
expand.
• This outer layer is made of gases and dust and is called the
planetary nebula.
• Core of the star heats up due to contraction,
• This stage is called the white dwarf.
• White dwarf finally cools down to become black dwarf