Transcript Black Holes
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 of the suns. 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 (most use hydrogen). The larger the star is, the faster it will use up 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 • 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 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 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 ► http://en.wikipedia.org/wiki/Black_hole ► ► ► ► ► ►