A black hole is a point in space where there is extreme gravitational pull, so extreme that light itself cannot escape. The strength of gravity is so strong due to the fact that an immense amount of matter has been contained in a small space. The existence of black holes was first theorized by John Mitchell in 1783. Mitchell accepted Newton’s laws of gravity and suggested that light escaping from the surface of a star would have its speed reduced due to the gravitation pull of the star, and therefore if a star’s gravitation pull was strong enough even light would not be able to escape. 1] Using the approximate speed of light he reasoned that if an object was approximately 500 times the mass of the sun light would not be able to escape and therefore be invisible. [2] Karl Schwarzchild was a German astrophysicist who used Einstein’s theory of relativity to compute and calculate the gravitation fields of stars. His solution to Einstein’s equation led him to calculate the radius of an object of particular mass for which light could not escape or in other words “that the fabric of time-space would fold in on itself, creating a ‘singularity’ – a region with zero volume and infinite density. [3]
There are various methods which have suggested and convinced astronomers that black holes exist. In particular, a technique used by astronomers to locate both stellar and super-massive black holes is to observe the motion of stars in the area around the supposed black hole. [4] Most stars in our galaxy are formed in groups of two or more stars, by observing the visible partner of a binary system, astronomers can effectively trace a black hole. Astronomers can calculate the mass of a black hole quite simply, using Keplar’s laws of motion, this is done by determining the velocity at which the partner star is orbiting the black hole.
The Term Paper on Black Holes Star Hole Light
... point, light from both the star and that hitting the field from the other sources cannot escape, thus a black hole is born. Black holes ... things as they collapse, including white dwarfs, neutron stars, and black holes. A black hole is suggested to be the end product of ... for astronomers to observe when looking for a black hole. Einstein s theory of general relativity suggests that close to the star ...
Generally if an object has a mass three times the sun or less it is a neutron star, if it is greater than that it is most likely a black hole. [5] Another method used by astronomers requires the use of x-ray detectors. Stars usually do not emit high amounts of x-rays, however as a companion star orbits closer to the black hole, it will speed up and gases emitted from the star will be pulled in by the immense gravity of the black hole. As this matter spirals into the black hole it creates what is known as an accretion disk, which accelerates and heats up emitting X-rays which can then be detected by astronomers. 6] Furthermore existence that black holes exist comes from the observations of astronomers of bursts of energy which are detected and then lost. An event horizon is an area of space around a black hole for which nothing can escape, once an object or any matter crosses this event horizon the gravity of the black hole will be too strong for it to escape. As a cloud of gas swirls and nears a black hole, the gases heat up and will emit x-rays. Astronomers have observed instances of several burts of x-rays being detected and then disappearing at areas where black holes are thought to be found.
This may be caused by the gases emitting x-rays and then crossing the event horizon and disappearing forever. The observations of these bursts of energy are useful for astronomers in finding black holes. ”GX 339-4, illustrated here, is among the most dynamic binaries in the sky, with four major outbursts in the past seven years. In the system, an evolved star no more massive than the sun orbits a black hole estimated at 10 solar masses. “ [5] However the strongest evidence of black holes comes from our very own galaxy, The Milky Way.
At the centre of our galaxy astronomers have found what is believed to be a super-massive black hole. First of all what led astronomers to believe that there lies a black hole at the centre of our galaxy? By monitoring and observing numerous stars that lie in the centre of our galaxy astronomers have found that the majority of these stars have orbits consistent with orbiting stars, i. e. they have elliptical shaped orbits. This suggests that the gravity which makes these stars orbit in such a fashion derives from a single object at their centre.
The Term Paper on Black Holes Hole Horizon Time
Black Holes. Fact or Fiction? Over the years black holes have been portrayed as portholes to other dimensions or times, gates across the galaxy, objects of death and destruction, or all of the above. Black holes are real, that is one of the few things that we do know about them for sure; we also believe that we have a firm grasp on how they are created and what they do, but their purpose still ...
By using the data taken from these stars and their orbits astronomers have been able to determine the mass of the object which they appear to be orbiting; astronomers have found that there lies a mass of “4 million solar masses within a region about the size of our solar system. ” [6] This suggests that there is in fact a black hole at the centre of our galaxy. Further evidence of a black hole in the centre of our galaxy arose from a study of the centre of our galaxy, focused on a known radio source referred to as Sagittarius A.
The centre of our galaxy is abundant with tiny dust particles, preventing visible light observations. Astronomers therefore were only able to used x-rays or infared too observe this part of our galaxy. American astronomers Bruce Balick and Robert Brown were one of the firsts to recognise the radio source known as Sagittarius A. [7] This discovery lead to a closer obsesrvation of Sagittarius A, with findings of extremely high speed gas and stars orbiting around the centre of the Milky Way, suggesting the existence of a black hole.
Years later, The Chandra X-ray facility observed a source of X-rays that were consistent with the location of Sagittaruius A, a burst of x-rays corresponded to what astronomers believe to be material falling into the black hole. The material heats up as it approaches the object, emitting x-rays and then the radio source fades as the object or material falls past the event horizon. [6] “supermassive black hole Sagittarius A* at the center of the Milky Way. (X-ray: NASA/CXC/MIT/F” The origin of a black hole is believed to be formed when a star’s mass is large enough that its gravity will cause it to collapse on itself.
Nuclear fusion a process that occurs in the core of stars allows a star to take the form that it does, as elements fuse together an immense amount of energy is created, this energy prevents a star from collapsing under its own gravity. However as the life of a star nears its end the forces that keep a star together diminish causing a star to compress and contract. Eventually all the fuel keeping the star ‘alive’ is depleted and the star collapses. If a star has enough mass, it will contract into a black hole shrinking to a critical size or radius known as the Schwarzschild radius as mention above, these are known as stellar black holes.
The Essay on Stars And Black Holes
By Beatrice A. Lopez Below you will read research on stars and black holes. Black holes are stars whose core has been crushed by gravity. In the text to follow you will see how a star forms, read about its life and how it becomes a black hole. Stars are composed of hydrogen gas and dust. Stars owe their existence to the force of gravity. Stars are created from the thinly spread atoms of dust and ...
Less massive stars will remain as a white dwarf or a neutron star. [8] On the other hand there are super-massive black holes which are of hundreds to millions of solar masses. These black holes are present in the centre of most galaxies and there has been much speculation as to where they come from. Some astronomers believe that they formed at the same time the galaxy was formed, which may explain its size. Until recenty astronomers were doubtful of the existence of mid-sized black holes however recent evidence may suggest that they do in fact exist, with stellar mass black holes merging with one another to form bigger mid-sized ones. 9] Another possible explanation of formation of super-massive black holes suggests that mergers between protogalaxies create ideal conditions for supermassive black holes to form. As the protogalaxies merge a collection of gas creates an unstable nuclear gas disk of a few billion solar masses. The cloud of gas collapses from its overwhelming gravity which will eventually lead to the formation of a supermassive black hole [10] So where do we find black holes? Not just the Milky Way, astronomers know that it is likely that there exists a supermassive black hole in the centre of most galaxies, for example M87 of the virgo cluster.
We know have evidence to believe that black holes are actually quite common in our universe. Locations of quasars are also suggested to be associated with black holes. Quasars are the brightest and most distant objects in our universe; they have a large redshift which may indicate they extreme rate at which they are moving away from the Earth. Quasars are known to be located in the centre of distant galaxies and emit enormous amounts of energy in the form of x-rays. The current theory is that in the centre of quasars lie supermassive black holes which power them.
The Essay on Black Holes 3
BLACK HOLES Mike Carey Scientists have been trying to determine if black holes (earlier known as `frozen stars ) truly do exist for several decades now. Thanks to the great Albert Einstein and his theory of relativity, researchers have been able to predict the cosmic phenomenon of black holes. A black hole is basically an area of space that has an unbelievably high area of concentrated mass for ...
