When a star "dies" it can do many different things. It can form a neutron star, expand to a red giant and shrink into a white dwarf, or sometimes collapse upon itself to form a black hole. This is mostly dependent on the density of the star. When massive stars, those twenty times the mass of our Sun or more die, they must either exhaust all of their excess mass or implode upon themselves and form black holes. Gravity overwhelms even the nuclear forces. The gravitational force becomes so strong that nothing can escape it, even photons of light, hence the name "black" hole.
It is believed that large black holes may exist at the center of our galaxy as well as others. The massive gravitational force that they exert would be enough to keep the body of the galaxy in orbit.
A black hole consists of a few key things. The singularity is the center of the black hole, the point at which the matter is being compressed into a massive density. The event horizon is the point at which not even photons of light can escape the tremendous gravitational pull of the black hole. This makes it hard ...
Starting with black holes, Khalili describes the creation of one. I found that a black hole is what remains when a massive star dies. Because stars are so massive and made out of gas, there is an intense gravitational field that is always trying to collapse the star. As the star dies, the nuclear fusion reactions stop because the fuel for these reactions gets burned up. At the same time, the star's gravity pulls material inward and compresses the core. As the core compresses, it heats up and eventually creates a supernova explosion in which the material and radiation blasts out into space. What remains is the highly compressed and extremely massive core. The core's gravity is so strong that even light cannot escape. This object is now a black hole and literally cannot be seen because of the absence of light. Because the core's gravity is so strong, the core sinks through the fabric of space-time, creating a hole in space-time. The core becomes the central part of the black hole called the singularity. The opening of the hole is called the event horizon. Khalili describes that there are two different kinds of black holes:
There is evidence that supports the hypothesis that the Milky Way Galaxy has a massive black hole at its core. At the center of our very own galaxy is a mysterious source of energy. Vast amounts of radiation pour from this compact source which may be a Supermassive Black Hole. Astronomers found an intense radio source with strings of other radio sources clustered about it in the direction of the galactic center. The intense source was named Sagittarius A because the center of the galaxy lies in the direction of the constellation Sagittarius. The position of Sagittarius A as has been observed through radio telescopes around the world seems to be very near the dynamical and gravitational center of the galaxy. Based on its high luminosity and radio spectrum Sagittarius A is neither a star nor a pulsar. It has a luminosity of 5 stars but is smaller than our solar system. Also, it can’t be a supernova remnant since it is not expanding. The strongest evidence that it is a Supermassive Black Hole come...
A black hole is what’s left after a star has collapsed and died of old age, its gravitational force was so strong, the star could no longer withstand. This makes the dead star exert very strong forces of gravity, making escape once entering the event horizon of a black hole impossible. This event horizon is most commonly simplified as, “the point of no return,” because it’s most likely impossible for anything to escape its horrendous force. Somebody that whiteness’s this would seem as if the object that entered the event horizon will become slower and slower as if it will never pass through. The object will become redshiftted as time passes, no light is emitted from the hole to someone witnessing, but to whatever is passing through then it will pass as if time remains normal. Some do believe that black holes will eventually die by evaporating, it will leave behind lots of radiation.
The responsibility of super massive black holes is to hold the galaxies together. (Millis 2014) Super massive black holes are very dense and its believed that their density can reach infinity in a way that even light can't pass through their gravitational force. (NRAO 2014)
...f gas, which collapsed and broke up into individual stars. The stars are packed together most tightly in the center, or nucleus. Scientists believe it is possible that at the very center there was too much matter to form an ordinary star, or that the stars which did form were so close to each other that they coalesced to form a black hole. It is argued that really massive black holes, equivalent to a hundred million stars like the Sun, could exist at the center of some galaxies
A Black Hole is defined as an object in space that is so compact, that has a gravitational pull so powerful, not even light can escape its pull. In most cases Black Holes are formed when a massive star (much larger than our own) undergoes a supernova explosion. When this happens, the star may collapse on its own gravitational pull, thus resulting in a an object with infinitely large density and zero volume. As a result, the escape velocity (the speed required to escape the gravitational pull) becomes even greater than the speed of light, and because nothing can travel faster than the speed of light, nothing can escape a black hole.
gravity and you end up with no star at all. The final one is the
...ke for instance the two images below. The first is a two-dimensional representation of the gravity of a normal star. Imagine any object floating through space as a marble. Said marble rolling along the flat surface of the space will roll into the indentation made by the sun's gravity. If you flick the marble hard enough, it can roll out of the indentation and roll away. The second pic is a representation of the gravity made by a black hole. Notice that if the marble rolls into the hole, there's no way it can get out, since there is no end to the hole.
We can also prove that dark matter exists in galaxies by examining how they spin. When an object rotates in a circular orbit, the object has a tendency to fly off in a path tangent to the orbit. If the stays within the orbit, it has a radial acceleration which is equal to its velocity squared over the radius of the orbit. The only force which is keeping the body in the orbit is the force of gravity, which is dependent on the mass of the system. Knowing this, physicists can calculate the mass of a galaxy by looking at how fast stars orbiting its center are moving. Physicists can also calculate where the highest percentage of dark matter should be in the galaxy. In most cases, it is located in a ring just outside the galaxy. In the case of the galaxy shown in the photo, dark matter must be present in the dark space between the nucleus of older yellow stars and the outer ring of young, blue stars.
Stars are born and reborn from an explosion of a previous star. The particles and helium are brought together the same way the last star was born. Throughout the life of a star, it manages to avoid collapsing. The gravitational pull from the core of the star has to equal the gravitational pull of the gasses, which form a type of orbit. When this equality is broken, the star can go into several different stages. Some stars that are at least thirty times larger than our sun can form black holes and other kinds of stars.
Black holes were originally thought to have only mere mathematical concepts. There was seemingly no possible way to compress any object into a space small enough to equal to its schwarzschild radius. Later however, astronomer Subrahmanyan Chandrasekhar calculated that stars much larger than our own sun should theoretically be able to collapse into a black hole (UTFC). A star is like a blown up balloon with the force of gravity trying to compress the balloon inwards and the air trying to push the balloon outwards. Likewise, stars are held in balance by gravity trying to collapse the star inwards going against the outwards pressure of the internal reactions of the star called nuclear fusion. If the star is big enough and the pressure inside quickly disappears, gravity would and should slingshot the star into a tiny point with near infinite density with an extremely strong gravitatio...
The Effects of Gravity There are some people who worry when they're outside, if they don't keep a good grip on the ground, they'll just go flinging off into space. They needn't really worry. about this, because gravity generally keeps that sort of thing from happening. The thing is, no one is really sure what causes gravity, but the effects have been studied by many. physicists and astronomers of the world.
...k around the black hole. There is another theory that the supermassive black hole at the center of our galaxy could swallow the Sun, which could result in a drastic and possible deadly effect on the orbits of the planets in our solar system (Wethington).
Astronomers believe that most galaxies consist of a supermassive black hole at the center, which attracts all constituents of galaxies such as, dust, gases (mainly Hydrogen and Helium), atoms, stars, interstellar clouds and planets to the center by force of gravity, but are not sure whether all galaxies contain a black hole in the center. Galaxies keep moving in relative motion to one another and intermittently can come so close that the force of gravitational attraction between the galaxies may become strong enough to cause a change in the shape of the galaxies, while in exceptional cases, the galaxies may collide. If two galaxies collide, they may pass right through without any effect or may merge, forming strands of stars, extending beyond 100,000 light years in space (World Book Online Reference Centre, 2005). Hence, neighboring and often other colliding galaxies induce the sha...
The Sun, in turn, is moving in an undulating orbit around the centre of the MIlky Way at 800,000 km/h (ka-boom would be 15 TJ - about a 3.5 kiloton baby nuke), which in turn is moving with the Local Group towards the Virgo Cluster, which in turn...... and so on and so on.