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 starts in the

universe ( by volume)Most Red giants radius is between 200 and

800 times of the suns.

How they Form

• Stars are powered by nuclear fuel (mostly use hydrogen). The larger the star is, the faster it will use up its fuel, so it will die sooner. The gravitational pull will crush the star to ‘zero volume’. ( or schwarzinchilds radius) This forms a Black Hole.

Schwarzschild RadiusSchwarzschild Radius

Schwarzschilds RadiusSchwarzschilds Radius- is the radius of a Event - is the radius of a Event Horizon of a Black Holes. According to Horizon of a Black Holes. According to Schwarzschild's solution, a gravitating object will Schwarzschild's solution, a gravitating object will collapse into a black hole if its radius is smaller collapse into a black hole if its radius is smaller than a character distance.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

• There are 3 types of Black Holes According to the size

Steller Black HolesSupermassive 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

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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 releases 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, Scientist will never know.

• Scientist 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- is 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 X-rays can be detected from earth.

Parts of a Black Hole

Singularity Event HorizonErgosphere

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- It is 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- Rotating Black Holes 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 the direction of the rotation.

Spacetime• Spacetime- 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 4- dimensional ( length, width, height and time)

Parts of a Black HolesParts of a Black Holes

Around many Black Holes there is a Around many Black Holes there is a Accretion Disk.Accretion Disk.

Accretion DiskAccretion Disk is material emitting energy is material emitting energy as it falls into the Black hole.as it falls into the Black hole.

Black Holes Colliding ??• It is a very rare for two Black Holes to make contact

with each other.• If it was to happen, the Black Hole will has 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 LastHow Long they Last

Even a Black Hole has finite life.Even a Black Hole has finite life. As a Black Hole radiates energy, it shrinks and As a Black Hole radiates energy, it shrinks and

the more it shrinks, the more it radiates, and so the more it shrinks, the more it radiates, and so finally it will completely evaporate. finally it will completely evaporate.

However this processes takes extremely long.However this processes takes extremely long. A Black Hole with a mass of the Sun will take A Black Hole with a mass of the Sun will take

more than “billon times a billon times a billon more than “billon times a billon times a billon times a billon times a billon times a billon times ” times a billon times a billon times a billon times ” the age of the universe to evaporate completely.the age of the universe to evaporate completely.

Video’s about Black Video’s about Black HolesHoles www.ted.com/.../andrea_ghez_the_huntwww.ted.com/.../andrea_ghez_the_hunt

_for_a__for_a_supermassivesupermassive__blackblack__holehole.html.html16:26 minutes long 16:26 minutes long

Find out more information about the Find out more information about the Schwarzschild radius and Supermassive Schwarzschild radius and Supermassive Black Holes.Black Holes.

http://www.youtube.com/watch?v=ou3Tukaucchttp://www.youtube.com/watch?v=ou3TukauccM&NR=1M&NR=1

1:45 minutes long1:45 minutes long

Watch a Black Hole destroying another starWatch a Black Hole destroying another star