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Black Holes

Black Holes On December 3, 1995, astronomers using the Hubble Space Telescope identified a black hole in the galaxy NGC 4621, located 100 million light-years from Earth in the direction of the constellation Virgo. This is the second super-massive black hole that astronomers using the Hubble Space Telescope have found. Astronomers believe that the mass of this black hole is about 1.2 billion times the mass of our sun, but it is concentrated in a space that is not any bigger than our solar system There are two puzzling questions that astronomers are trying to answer. The black hole is fueled by the galaxy and its 800 light-year-wide spiral disk of dust. Before the discovery of this black hole, astronomers did not think that there was any dust in elliptical galaxies like NGC 4261. Currently they believe that the disk of dust is the remnant of a smaller galaxy that fell into the core of NGC 4261.

The black hole will swallow up the gas from the smaller galaxy over the next 100 million years. Researchers believe that while the gas is being swallowed by the black hole, the process will produce some amazing fireworks. The second puzzling question that astronomers are trying to answer is why isnt the black hole at the center of the galaxy? According to images from the Hubble Space Telescope, the black hole is 20 light-years from the center of the galaxy, but since the black hole is so massive it is hard to explain how it could have been moved. One idea is that the black hole is moving itself. Some astronomers think that the disk of dust serves as a “fuel tank.” The black hole sucks in the material which is absorbed by gravity, compressed, and heated to tens of millions of degrees. This theory would explain why radio telescopes have observed radio jets, or hot gas exhausts from the black holes area.

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The exhaust may be pushing the black hole across space, as a jet engine gives thrust to a plane. According to Ted Bunn, an astronomer at Berkley University, “A black hole is a region of space that has so much mass concentrated in it that there is no way for a nearby object to escape its gravitational pull, not even light.” So, what does that mean? The following example will explain the nature of a black hole. A ball is thrown up into the air. It rises for a while, but it eventually falls. If the ball is thrown fast enough it is able to escape the gravitational field and continue rising. This is called the “escape velocity.” The escape velocity depends on the mass of the planet, which affects the gravitational field.

A object on Earth would have to travel at 25,000 m.p.h. to escape the gravitational pull of Earth. Now imagine an object with a gravitational pull so large and escape velocity so high that even visible light could not escape it. This is a black hole. How are black holes formed? To our best knowledge, black holes are created at the end of a very large stars life cycle.

The star collapses into a white dwarf, which is the smallest, dimmest, and hottest of all stars. Matter is packing continually tighter and tighter together and gravity is increasing. The white dwarf will collapse into itself when it runs out of fuel, thus creating a black hole. Therefore only very massive stars can form black holes because only large stars have enough mass and gravitational pull to collapse into itself. What are the parts of a black hole? There are two main parts to a black hole. The first one is the event horizon and the second is the singularity.

The event horizon is the spherical surface that marks the boundary of the black hole. You can pass into the black hole through the horizon, but you cannot pass back out of it. Once you have crossed the horizon, you are doomed to “hit” singularity. The singularity is the center of the black hole and all that astronomers know about it is that the gravitational pull is so large that anything reaching it would be torn to pieces. Astronomers are continuing to research photos of the black hole in the galaxy NGC 4261 sent back by the Hubble Space Telescope.

These photos will hopefully help astronomers to better understand the mysteries of black holes. Bibliography 1. Anonymous. “Black Holes.” http://ericir.syr.edu/Projects/Newton/11/blchole.h tml (27 Aug. 1996) 2. Asimov, I.

(1978) How Did We Find Out About Black Holes? New York: Walker and Company 3. McIrvin, Matt. “Some Frequently Asked Questions About Black Holes.” http://skyron.harvard.edu/bh faq.html (15 Sept. 1996) 4. The Students of the Astronomy Department of the University of Cambridge. “Observational Evidence for Black Holes”, “Introduction to Black Holes”, and “Black Holes and Critical Phenomena.” http://damtp.cam.ac.uk/gr/public/ (27 Aug.

1996).

BLACK HOLES

BLACK HOLES
Into the Depths of A Black HoleEveryday we look out upon the night sky, wondering and dreaming of what lies beyond our planet. The universe that we live in is so diverse and unique, and it interests us to learn about all the variance that lies beyond our grasp. Within this marvel of wonders our universe holds a mystery that is very difficult to understand because of the complications that arise when trying to examine and explore the principles of space. That mystery happens to be that of the ever clandestine, black hole.This essay will hopefully give you the knowledge and understanding of the concepts, properties, and processes involved with the space phenomenon of the black hole. It will describe how a black hole isgenerally formed, how it functions, and the effects it has on the universe. In order to understand what exactly a black hole is, we must first take a look at the basis for the cause of a black hole. All black holes are formed from the gravitational collapse of a star, usually having agreat, massive, core. A star is created when huge, gigantic, gas clouds bind together due to attractive forces and form a hot core, combined from all the energy of the two gas clouds. This energy produced is so greatwhen it first collides, that a nuclear reaction occurs and the gases within the star start to burn continuously. The Hydrogen gas is usually the first type of gas consumed in a star and then other gas elements such as Carbon, Oxygen, and Helium are consumed.This chain reaction fuels the star for millions or billions of years depending upon the amount of gases there are. The star manages to avoid collapsing at this point because of the equilibrium achieved by itself. The gravitational pull from the core ofthe star is equal to the gravitational pull of the gases forming a type of orbit, however when this equality is broken the star can go into severaldifferent stages.Usually if the star is small in mass, most of the gases will beconsumed while some of it escapes. This occurs because there is not atremendous gravitational pull upon those gases and therefore the starweakens and becomes smaller. It is then referred to as a White Dwarf. If the star was to have a larger mass however, then it may possiblySupernova, meaning that the nuclear fusion within the star simply goes out of control causing the star to explode. After exploding a fraction of the star is usually left (if it has not turned into pure gas) and that fraction of the star is known as a neutron star.A black hole is one of the last option that a star may take. If the core of the star is so massive (approximately 6-8 solar masses; one solar mass being equal to the sun’s mass) then it is most likely that when the star’s gases are almost consumed those gases will collapse inward, forced into the core by the gravitational force laid upon them.After a black hole is created, the gravitational force continues to pull in space debris and other type of matters to help add to the mass of the core, making the hole stronger and more powerful.Most black holes tend to be in a consistent spinning motion.This motion absorbs various matter and spins it within the ring (known asthe Event Horizon) that is formed around the black hole. The matter keeps within the Event Horizon until it has spun into the centre where it isconcentrated within the core adding to the mass. Such spinning black holes are known as Kerr Black Holes. Most black holes orbit around stars due to the fact that they oncewere a star, and this may cause some problems for the neighbouring stars. If a black hole gets powerful enough it may actually pull a star into it and disrupt the orbit of many other stars. The black hole could then grow even stronger (from the star’s mass) as to possibly absorb another. When a black hole absorbs a star, the star is first pulled into the Ergosphere, which sweeps all the matter into the Event Horizon, named forit’s flat horizontal appearance and because this happens to be the placewhere mostly all the action within the black hole occurs. When the star is passed on into the Event Horizon the light that the star endures is bentwithin the current and therefore cannot be seen in space. At this exactpoint in time, high amounts of radiation are given off, that with theproper equipment can be detected and seen as an image of a black hole.Through this technique astronomers now believe that they have found a black hole known as Cygnus X1. This supposed black hole has a huge star orbiting around it, therefore we assume there must be a black hole that it is inorbit with. The first scientists to really take an in depth look at black holes and the collapsing of stars, were a professor, Robert Oppenheimer and hisstudent Hartland Snyder, in the early nineteen hundreds. They concluded on the basis of Einstein’s theory of relativity that if the speed of light was the utmost speed over any massive object, then nothing could escape a black hole once in it’s clutches. **(1)The name “black hole” was named such, because of the fact that lightcould not escape from the gravitational pull from the core, thus making the black hole impossible for humans to see without using technologicaladvancements for measuring such things like radiation. The second part of the word was named “hole” due to the fact that the actual hole, is whereeverything is absorbed and where the centre core presides. This core isthe main part of the black hole where the mass is concentrated and appears purely black on all readings even through the use of radiationdetection devices. Just recently a major discovery was found with the help of a device known as The Hubble Telescope. This telescope has just recently found what many astronomers believe to be a black hole, after being focused on an star orbiting empty space. Several picture were sent back to Earth from the telescope showing many computer enhanced pictures ofvarious radiation fluctuations and other diverse types of readings that could be read from the area in which the black hole is suspected to be in.Several diagrams were made showing how astronomers believe that if somehow you were to survive through the centre of the black hole that there would be enough gravitational force to possible warp you to anotherend in the universe or possibly to another universe. The creative ideas that can be hypothesized from this discovery are endless. Although our universe is filled with much unexplained, glorious,phenomenons, it is our duty to continue exploring them and to continue learning, but in the process we must not take any of it for granted.As you have read, black holes are a major topic within our universe and they contain so much curiosity that they could possibly holdunlimited uses. Black holes are a sensation that astronomers are still very puzzled with. It seems that as we get closer to solving their existence and functions, we just end up with more and more questions.Although these questions just lead us into more and more unanswered problems we seek and find refuge into them, dreaming that maybe one day, one far off distant day, we will understand all the conceptions and we will be able to use the universe to our advantage and go where only our dreams could take us.
Works Cited
Depths of a Black Hole**(1): Parker, Barry. Colliding Galaxies. PG#96

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