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the life cycle of a star
stars formation and existence
life cycle of a star
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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 gas that swirl throughout space. The atoms clump together into dense clouds that eventually collapse under their own gravity. Other forces counteract the gravity. The dust and cloud grows
steadily hotter until a nuclear furnace ignites creating a bright shining star. (Couper H. & Henbest N., 1996).
Stars are born when particles of hydrogen, helium and dust combine and collapse, shrinking and falling into itself making the cloud hotter. Tiny protons bump into each other and bounce away at high speeds stick together when it is hot enough. Four protons form a particle of helium gas. Two protons fuse together becoming neutrons. Matter that is released from this fusion turns into energy streaming outward from the core creating nuclear fusion. Once the inward and outward forces are equal it reaches its final size and shines, becoming a star. The length of the hydrogen burning stage depends on the stars weight. A star with 15 times the weight of the sun uses up all its hydrogen in less than 10 million years. (Darling D., 1985)
The farthest star in the most distant galaxy is more than ten billion light years away. The kind of star
a star becomes depends on how much gas and dust the protostar manages to pack into itself as it forms. The more mass a star collects the hotter and brighter it becomes. (Gallant R ., 2000).
Three major star types are red dwarfs, yellow dwarfs and blue giants. Red dwarfs are the dimmest and have the longest life span that is about a trillion years. Red dwarfs become black dwarfs when they exhaust their hydrogen and fuel. Yellow dwarf stars have shorter life spans because they burn their hydrogen fuel faster. As fuel runs low they swell up into a red giant, then release planetary nebula, then shrink into white dwarfs and finally cool as black dwarfs. The massive blue giants have the shortest life span as they’ll swell up into supergiants, explode as a supernova and end up as either a neutron star or black hole. (Gallant R .,
2000).
A norm...
... middle of paper ...
...un is a ball of gas. It is 8 and one third light years
away and 93 million miles away. The suns diameter is 865,000 miles. The sun is about 5 billion years old. (Darling D., 1985).
The sun appears as a large disk. At the top of the
sun you can see two huge gas eruptions called prominences. These prominences leap out hundreds of thousands of miles. They have hair like spikes that are surges of hot gas called spicules. The mottled effect is caused by cells of hot gases welling up from beneath the surface, cooling and appearing darker than the surrounding gases. (Gallant R ., 2000).
Therefore, the sun, stars and black holes coexist with one another in the solar system
along with other matter in the galaxy. The sun is a star. Black holes are collapsed stars. Each does not exist without the other.
References
Couper H. & Henbest N. (1996). Black Holes. New York, NY: DK Publishing Inc.
Darling D. (1985). The Stars from birth to black hole. Minneapolis, Minnesota: Dillon
Press Inc.
Gallant R . (2000). The life stories of Stars. Tarrytown, New York: Benchmark Books
Sipiera P. (1997). Black Holes. Canada: Children’s Press, Grolier Publishing Co. Inc
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:
The origins of the super-massive black holes which concludes how they were formed and what caused them to form is an unsolved problem which is yet a mystery of astrophysics. ( Millis 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.
Black holes - the strange scientific phenomenon that has astounded physicists and astronomers alike for decades. Popular subjects in science fiction novels, black holes are one of the greatest enigmas of the scientific world. Even today, the concept of a super-dense ball of matter that not even light can escape from is somewhat farfetched, and many scientists disagree with each other about nearly every aspect of a black hole. This project will attempt to shed some light on these mysterious formations, and will inform you the reader of the most popular and widely accepted theories surrounding them.
A Black hole is a theorized celestial body whose surface gravity is so strong that
The American scientist John Wheeler coined the phrase “black hole” in 1969 to describe a massively compact star with such a strong gravitational field that light cannot escape. When a star’s central reserve of hydrogen is depleted, the star begins to die. Gravity causes the center to contract to higher and higher temperatures, while the outer regions swell up, and the star becomes a red giant. The star then evolves into a white dwarf, where most of its matter is compressed into a sphere roughly the size of Earth. Some stars continue to evolve, and their centers contract to even higher densities and temperatures until their nuclear reserves are exhausted and only their gravitational energy remain. The core then rushes inward while the mantle explodes outward, creating neutron stars in the form of rapidly rotating pulsars. Imploding stars overwhelmed by gravity form black holes, where the core hits infinite density and becomes a singularity (some estimate it at 10^94 times the density of water).
Every day we look into the night sky, wondering and dreaming what lies beyond our galaxy. Within our galaxy alone, there are millions upon millions of stars. This may be why it interests us to learn about all that we cannot see. Humans have known the existence of stars since they have had eyes, and see them as white glowing specks in the sky. The mystery lies beyond the white glowing specks we see but, in the things we cannot see in the night sky such as black holes.
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.
A star begins as nothing more than a very light distribution of interstellar gases and dust particles over a distance of a few dozen lightyears. Although there is extremely low pressure existing between stars, this distribution of gas exists instead of a true vacuum. If the density of gas becomes larger than .1 particles per cubic centimeter, the interstellar gas grows unstable. Any small deviation in density, and because it is impossible to have a perfectly even distribution in these clouds this is something that will naturally occur, and the area begins to contract. This happens because between about .1 and 1 particles per cubic centimeter, pressure gains an inverse relationship with density. This causes internal pressure to decrease with increasing density, which because of the higher external pressure, causes the density to continue to increase. This causes the gas in the interstellar medium to spontaneously collect into denser clouds. The denser clouds will contain molecular hydrogen (H2) and interstellar dust particles including carbon compounds, silicates, and small impure ice crystals. Also, within these clouds, there are 2 types of zones. There are H I zones, which contain neutral hydrogen and often have a temperature around 100 Kelvin (K), and there are H II zones, which contain ionized hydrogen and have a temperature around 10,000 K. The ionized hydrogen absorbs ultraviolet light from it’s environment and retransmits it as visible and infrared light. These clouds, visible to the human eye, have been named nebulae. The density in these nebulae is usually about 10 atoms per cubic centimeter. In brighter nebulae, there exists densities of up to several thousand atoms per cubic centimete...
If the nebula is dense enough, certain regions of it will begin to gravitationally collapse after being disturbed. As it collapses the particles begin to move more rapidly, which on a molecular level is actually heat, and photons are emitted that drive off the remaining dust and gas. Once the cloud has collapsed enough to cause the core temperature to reach ten-million degrees Celsius, nuclear fusion starts in its core and this ball of gas and dust is now a star. It begins its life as a main sequence star and little does it know its entire life has already been predetermined.
Our sun is the central pivot point to which or entire planet and solar system is built around. With out it all life on our planet would cease to exist. Within this paper we will explore how our Sun and solar system formed and came to resemble what we see today.
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Black holes are the result of the death of a massive star, leaving behind a dense remnant core that eventually collapses to create a gravitational force so strong that nothing, including light, can escape the force. The theory that black holes existed started back in the early 1900s and since then astronomers and scientists have been trying to get a better understanding of them. This phenomenon has been a working progress for astronomers and scientists for many years and as we develop a better understanding of our solar system, the more likely it is to make a significant discovery that can answer some of the most difficult questions about our incredible galaxy and solar system. The more information we are able to acquire about our universe, the more questions we might be able to answer about our existence. With advancements in technology we may be able to see some significant discoveries and insights into the world of black holes.