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What is the theorized "life cycle" of a star
Stars formation and existence
The life cycle of a star
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Life Cycle of a Star Our Sun is a perfect example of a star, and there is an incredible amount of stars in the Universe. It is a star among hundreds of billions of stars within our Milky Way Galaxy, and our galaxy is one of billions of galaxies in the universe. Stars live for a very long time; millions, billions, or tens of billions of years so we can never really observe the life of a star; its birth, life, and death. In determining the life cycle of a star, astronomers observe many of the billions of stars around us and see them at different stages of life, therefore piecing together a star's evolution. A star is born from clouds of gas and dust called nebulae found in interstellar space. Nebulae are composed mainly of hydrogen and helium, but also contain traces of heavier elements. It is uncertain as to how the very first stars were created. What is known is that after the first stars were formed, they began to generate energy which in turn heated up its surrounding gas in the nebula. The gas, once heated began to expand and its pressure and density increased. A few of the very first stars were massive and short lived, quickly finishing their supply of fuel and exploding. From theses explosions, hot gas was emitted into the surrounding nebula increasing the pressure and density even more. When the pressure and the gas density got too high, the gravity between molecules was able to bring its particles together. Matter then began to separate and fall into common centers. When the dust and gas was united, particles accelerated under its force of gravity and began colliding with one another. These collisions caused a small area in the cloud to become very hot and dense. This heat caused the molecules t... ... middle of paper ... ...is between millions to tens of billions of years, but being able to view many of these stars much like the observation of a human life, astronomers have been able to produce a stars life cycle. Some of the observations and conclusions are merely theoretical, such as the notion of a black hole. However, just because we cannot see it does not mean that it is not there. Works Cited Bennett, Jeffery, Megan Donahue, Nicolas Schneider, Mark Voit. The Solar System: selected chapters from The Cosmic Perspective Third Edition. San Francisco: Pearson Education Inc., 2004. Encyclopedia Britannica Concise CD-Rom. 2001. Encyclopedia Britannica Inc. Thompson, Graham R., Jonathan Turk. Earth Science and the Environment Second Edition. Orlando: Harcourt Brace & Company, 1999 Slides and notes from lectures in class on chapter 16, 15 Aug. 2005.
Cunningham, William P. Cunningham, Mary Ann and Saigo, Barbara. Environmental Science, A Global Concern. McGraw-Hill. New York, NY. 2005.
Stars explode at the end of their lifetime, sometimes when they explode the stars leave a remnant of gasses and, dust behind. What the gasses come together to form depend on the size of the remnant. If the remnant is less than 1.4 solar masses it will become a white dwarf, a hot dead star that is not bright enough to shine. If the remnant is roughly 1.4 solar masses, it will collapse. “The protons and electrons will be squashed together, and their elementary particles will recombine to form neutrons”. What results from this reaction is called a neut...
The extreme brightness of the O-type and B-type stars, coupled with the Earth’s atmosphere, has always made high-resolution imaging of the star-forming region difficult. But recent advances in adaptive optics and the repair of the Hubble Space Telescope have allowed for incredible detail into the center of the dust cloud. 3 The technological advances have also helped reveal several faint stars within the center of the nebula.
Solar nebula is a rotating flattened disk of gas and dust in which the outer part of the disk became planets while the center bulge part became the sun. Its inner part is hot, which is heated by a young sun and due to the impact of the gas falling on the disk during its collapse. However, the outer part is cold and far below the freezing point of water. In the solar nebula, the process of condensation occurs after enough cooling of solar nebula and results in the formation into a disk. Condensation is a process of cooling the gas and its molecules stick together to form liquid or solid particles. Therefore, condensation is the change from gas to liquid. In this process, the gas must cool below a critical temperature. Accretion is the process in which the tiny condensed particles from the nebula begin to stick together to form bigger pieces. Solar nebular theory explains the formation of the solar system. In the solar nebula, tiny grains stuck together and created bigger grains that grew into clumps, possibly held together by electrical forces similar to those that make lint stick to your clothes. Subsequent collisions, if not too violent, allowed these smaller particles to grow into objects ranging in size from millimeters to kilometers. These larger objects are called planetesimals. As planetesimals moved within the disk and collide with one another, planets formed. Because astronomers have no direct way to observe how the Solar System formed, they rely heavily on computer simulations to study that remote time. Computer simulations try to solve Newton’s laws of motion for the complex mix of dust and gas that we believe made up the solar nebula. Merging of the planetesimals increased their mass and thus their gravitational attraction. That, in turn, helped them grow even more massive by drawing planetesimals into clumps or rings around the sun. The process of planets building undergoes consumption of most of the planetesimals. Some survived planetesimals form small moons, asteroids, and comets. The leftover Rocky planetesimals that remained between Jupiter and Mars were stirred by Jupiter’s gravitational force. Therefore, these Rocky planetesimals are unable to assemble into a planet. These planetesimals are known as asteroids. Formation of solar system is explained by solar nebular theory. A rotating flat disk with center bulge is the solar nebula. The outer part of the disk becomes planets and the center bulge becomes the sun.
6th ed. of the book. New York, NY: McGraw-Hill, 2011. Print. The.
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.
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...
Our solar system, as we see it today, originally formed from the collapse of a very cold and low-density cloud of gas. The mass of this cloud was composed of 98% hydrogen and helium, 1.4% hydrogen compounds, .4% rock, and .2% metal. The nebula was thought to be a few light years across and was roughly spherical in shape. The cloud was in a state of balance, it was neither contracting or expanding, until a cataclysmic event, most likely a supernova, created a shock wave through the nebula, resulting in an area of higher mass. Once this area became more massive than the rest of the nebula it begin to collapse with the area of hig...
Supernovas are extremely powerful explosions of radiation. A supernova can give off as much energy as a Sun can within its whole life. A star will release most of its material when it undergoes this type of explosion. The explosion of a supernova can also help in creating new stars.
The idea behind the Solar Nebular Hypothesis is that the solar system was condensed from an enormous cloud of hydrogen, helium, and a few other elements and rocks. Around five billion years this cloud of materials began to spin and contract together into a disk shape under their own gravitational forces. The particles started combined together, protoplanets, to eventually form planets. A great mass of the material eventually began to form together, protosun, and make up the sun.
Raven, Peter H., Linda R. Berg, and David M. Hassenzahl. "Wiley: Environment, 6th Edition." Wiley: Home. Web. 05 Feb. 2012. .
The first person to ever observe the Milky Way was Greek philosopher, Democritus, who said the galaxy may consist of distant stars. In 1610, Galileo Galilei used a telescope to study the Milky Way and came to the conclusion that it was composed of billions and billions of faint stars. Then, in 1750, Thomas Wright c...
Generally, the universe began as a composition of radiation and subatomic particles, which proceeded with galaxies formation. Galaxies are made up of hydrogen, helium, 100-200 billions of stars, planets and most having a black hole at the center, which attracts everything present in galaxies by force of gravity. Galaxies can be classified as either spiral (Milky Way- galaxy which human kind has been found to exist), elliptical, lenticular and irregular, where the structure is determined by neighboring galaxies with most galaxies are moving away from each other. Classification of galaxies is being conducted by online programs such as Galaxy zoo, using pictures from telescopes and is making significant progress.