Transcript Black Holes - MsRotchfordsClass

By Katy O’Donohue
Black Holes
• Black Holes are a region of space from which
nothing can escape, including light.
• Light is made up of massless particles (even
massless particles can’t escape)
• It is called “black” because it absorbs all the
light that hits it, reflecting nothing.
• Black Holes start from a collapse of a
red super giant star.
Red Super giant- they are the largest
stars in the universe ( by volume)
Most Red Super Giants radii are
between 200 and 800 times that of the
sun.
Schwarzschild Radius
Schwarzschilds Radius- is the radius of a Event
Horizon of a Black Holes. According to
Schwarzschild's solution, a gravitating object will
collapse into a black hole if its radius is smaller
than a character distance.
is the Schwarzschild radius;
is the gravitational constant
is the mass of the gravitating object;
is the speed of light in vacuum
How they Form
• Stars are powered by nuclear fuel (mostly use
hydrogen). The larger the star is, the faster it
will use up it’s fuel, therefore, die sooner. The
gravitational pull will crush the star to ‘zero
volume’. ( or schwarzinchilds radius) This
forms a Black Hole.
• There are 3 types of Black Holes according to
the size
Steller Black Holes
Supermassive Black Holes
Miniature Black Holes
 This picture is NOT of stars, it is of supermassive Black Holes
churning away in at the center of distant galaxies
t
Stellar Black Holes
• Stellar Black Holes are the Black Holes that
are formed from a gravitational collapse of
a massive star at the end of its life time.
This event is known as a Supernovae.
• Supernovae is a huge release of tremendous
energy. As the star comes to an end, the
supernovae produces 1020 times as much
energy than our sun produces in one
second.
Supermassive Black Holes
• Supermassive Black Holes are the largest type
of Black Holes in a galaxy.
• Most galaxies are believed to have a
Supermassive Black Hole in the center
(including the Milky Way).
Miniature Black Holes
• Theory suggests that miniature black holes
might have formed in the early universe when
the “Big Bang” happened, which is thought to
have started the Universe 15 billon years ago,
but astronomers do not have any evidence of
their existence.
Is There a Black Hole in the center of
Our Galaxy?
• Scientist do believe that there is a Black Hole
in the center of our galaxy.
• In 1995, using the Keck l Telescope atop
Mauna Kea in Hawaii, Andrea Ghez began
tracking 200 stars in the center of our galaxy.
Ghez found at least 20 stars that had signs of
extreme gravitational forces.
• These stars are moving three million miles per
hour, about 10 times the speed at which stars
typically move.
Is There a Black Hole in the center of
Our Galaxy?
• After studying these stars, she witnessed a
disappearance of one of the stars that was, at the
time, the closest object to the Black Hole.
• Whether the star was sucked up by the Black Hole or
just went behind it, Scientists will never know.
• Scientists have little fear of the similar fate for earth
because the center of the Milky Way is
approximately 24,000 light years away.
– Light years: the distance light travels in one solar
year, roughly 5.9 trillion miles (the center of the milky way
is 141,600 trillion miles away)
Black Holes
• Black Holes can not be seen because matter (light)
and other forms of energy can not escape from
them, but they can be detected by other visible
objects around them.
• Scientists believe that before the matter gets sucked
up by the Black Hole, they swirl in a whirlpool and
the heated matter emit fluctuating X-rays. These Xrays can be detected from earth.
Parts of a Black Hole
Singularity
 Event Horizon
Ergosphere
Accretion Disk
Parts of a Black Hole
• Singularity: Lies in the center of the Black
Hole, where matter is crushed to infinite
destiny.
• Event horizon: A region of spacetime around
the Black Hole where there is a undetectable
surface that marks the point of no return.
Light and matter can only pass inward
towards the mass of the Black Hole. Nothing
can escape from inside the Event Horizon.
Parts of a Black Holes
• Ergosphere: A Rotating Black Hole
that has a region of space-time which
makes it impossible for it to stand still.
Any object near the rotating mass will
tend to start moving in the direction of
the rotation.
Spacetime
• Space-time: Combines space and time into a single
continuum. Spacetime is usually interpreted with
space being three-dimensional and time playing the
role of a fourth dimension
• Space is 3-dimensional (including length, width, and
height), but by adding time to it, it become 4dimensional ( length, width, height and time)
Parts of a Black Holes
Around many Black Holes there is a
Accretion Disk.
 Accretion Disk is material emitting energy
as it falls into the Black hole.

Black Holes Colliding ??
• It is very rare for two Black Holes to make contact
with each other.
• If that were to happen, the Black Hole would have
so much force and energy that the other Black Hole
will get kicked away (imagine two spinning tops
coming together)
• As one gets a kick, the other receives tremendous
amounts of energy, injected into a disk of gas
surrounding it. The Accretion disk will blaze a soft
X-ray flare that should last thousands of years.
How Long they Last
Even a Black Hole has finite life.
 As a Black Hole radiates energy, it shrinks.
The more it shrinks, the more it radiates,
and finally it will completely evaporate;
however, this process takes extremely
long.
 A Black Hole with a mass of the Sun will
take more than “a billon times a billon
times a billon times a billon times a billon
times a billon times” the age of the
universe to evaporate completely.

Video’s about Black Holes

www.ted.com/.../andrea_ghez_the_hunt_for
_a_supermassive_black_hole.html
16:26 minutes long
Find out more information about the Schwarzschild
radius and Supermassive Black Holes.
http://www.youtube.com/watch?v=ou3TukauccM&NR
=1
1:45 minutes long
Watch a Black Hole destroying another star
MY GLOG
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Also check out my glog at –
http://katy44.edu.glogster.com/glog4834/
At my Glog I answered questions that
you might have.
Research Plan
►
http://science.nationalgeographic.com/science/space/universe/blackhol
es-article.html
http://www.neiu.edu/~rerebecc/blackholes/facts.htmlhttp://www.kidsastronomy.com/black_hole.htm
http://superstringtheory.com/blackh/blackh3.html
http://www.wonderquest.com/black-holes.htm
http://cosmology.berkeley.edu/Education/BHfaq.html
http://www.scienceclarified.com/Bi-Ca/Black-Hole.html
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http://en.wikipedia.org/wiki/Black_hole
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