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Understanding stellar evolution
Stars formation and existence
An essay about space travel
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Recommended: Understanding stellar evolution
In astronomy, stellar evolution refers to the changes which stars undergo during their lifetime. Stars change in color, luminosity, size and temperature through their lifespan. Scientist can not study an individual stars lifetime though because they far exceed ours and therefore we must study stellar evolution by observing the life cycle of numerous stars, each at a different point in its life cycle, and then running computer models which simulate the structure of stars. Through history stars have been recorded, starting with the brightest, which have been named going back as far as 1000 b.c. by the chinese. Today we name stars in three categories, the first being the brightest are named for what constellation they are in. Variable stars are the ones that change in luminosity periodically and the fainter stars are logged in the Henry Draper Catalogue under numubers like HD 12938. Stars exist either alone or in groups of two or more in a system or cluster. Large clusters are grouped into galaxies and in our Galaxy, the Milky Way there are more than 100 billion stars. There are also 10's of millions of galaxies that are part of the known universe. Think about that and tell me there's no life out there. As technology permitted it was found that stars positions are not fixed and that stars move at various speeds measured in changes of direction in fractions of a second of arc per year. This second of arc is the angular size of a pinhead that is 183 m away (wow, now thats precise, you would think). Many of the fainter stars almost seem to not move at all though because they are so far away and thats why we use them as reference stars to measure others and scientists call this proper motion. A Parallex is another apparent m... ... middle of paper ... ...rs of a fraction of a second. Its neutrinos send a shockwave out blasting most of the stars materials into space, but many of the elements get caught up in neutrinos and combine to create heavier elements. Without supernovae there would be no heavier elements than Iron-56. It is not understood well, but in some supernovae the gravity is so intense within the red supergiant that the electrons are forced into the atomic nuclei where they combine with protons to form neutrons. The electromagnetic forces keeping apart the seperate nuclei are gone and the entire core becomes a dense ball of neutrons or an atomic nucleus about the size of Manhatten called a Neutron Star. If the mass is great enough though, when the star turns into a red supergiant it will collapse under its on gravity into a radius smaller than the Schwarzchild Radius and turn into a Black Hole.
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...
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:
...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.
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.
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.
Parallax is defined as “any alteration in the relative apparent positions of objects produced by a shift in the position of the observer” (Columbia Electronic Encyclopedia 1). Parallax is commonly used to measure distances between celestial bodies, such as planets and stars. Parallax is measured using angles that are much smaller than a degree. Arcminutes are one sixtieth of a degree and arcseconds are one sixtieth of an arminute. One example of the infinitesimal size of an arcsecond could be the width of a dime from a point of view two kilometers away (“Cool Cosmos”). These units of measurement are used in the parallax formula, or the formula used to calculate distance when given an object’s parallax measurement. The distance given from the parallax formula is in parsecs, which are 3.26 light years or 3.18x10^13 kilometers (“PARALLAX”). The parallax formula can be written as “distance = 1/parallax” (“PARALLAX”).
...e times the mass of the sun. In this case gravity is overwhelmingly strong and is able to crush the neutron star towards zero mass. The result is a black hole with a gravitational field strong enough to not even let light escape (Brusca, 2004).
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...
The Big Bang, the alpha of existence for the building blocks of stars, happened approximately fourteen billion years ago. The elements produced by the big bang consisted of hydrogen and helium with trace amounts of lithium. Hydrogen and helium are the essential structure which build stars. Within these early stars, heavier elements were slowly formed through a process known as nucleosynthesis. Nucleosythesis is the process of creating new atomic nuclei from pre-existing nucleons. As the stars expel their contents, be it going supernova, solar winds, or solar explosions, these heavier elements along with other “star stuff” are ejected into the interstellar medium where they will later be recycled into another star. This physical process of galactic recycling is how or solar system's mass came to contain 2% of these heavier elements.
A star will blow up with the help of gravitational collapses. When a star explodes from nuclear fusion it is because so much mass has built up within its core and it cannot hold the weight. Neutrons are the only things in nature that can stop a core implosion. When a white dwarf suffers a supernova, the energy comes from the runaway fusion of carbon and oxygen in the core.
As you can see we have been temporarily blinded from the truth by fictional things that are easy to believe and that we want to believe. There are so many incorrect theories and ideas and most of them are just plain ridiculous. Astronomy can be a very complicated subject, but it is very necessary to understand what really happens in our galaxy and out in the huge frontier we call space.
In an article in Scholastic, David Fisherman states, “Within seconds the fireball ejected matter/energy at velocities approaching the speed of light. At some later time—maybe seconds later, maybe years later—energy and matter began to split apart and become separate entities. All of the different elements in the universe today developed from what spewed out of this original explosion” (Fishman). The diagram above shows how vastly and rapidly the universe was created. During the inflation of the universe, it grew rapidly and doubled in size at least ninety times. While hot and dense, the universe expanded rapidly. Denise Chow wrote on space.com, “for the first 380,000 years after the Big Bang, the intense heat from the universe’s creation made it essentially too hot for light to shine. Atoms crashed together with enough force to break up into a dense, opaque plasma of protons, neutrons, and electrons that scattered light like fog” (Chow). After cooling, it allowed energy to be converted into particles such as protons, neutrons, and electrons. Within minutes after the Big Bang, atomic nuclei formed, but it took thousands of years before electrically neural atoms were first formed. The majority of atoms that formed were hydrogen, helium, and traces of lithium. Gravity caused the hydrogen and helium has to form giant clouds that will become galaxies, the smaller clouds broke apart to form stars, which was when the universe came out of its dark ages. Planets were formed by the first stars dying and releasing heavy elements into
The education system in India is based on forced learning that kills student’s spirit and zest of learning. In the film “Like Stars on Earth,” we look specifically at the draw backed role played by parents and teacher in Indian education system. We follow the story of a dyslexic Indian boy, Ishaan, who always had trouble coping with his studies, but in the end with the help of an understanding teacher he is able to study normally and catch up with his peers. We will analyze this film using the concepts from Practices of Looking to explain our thesis. Eddie will cover the concepts of encoding and the ideology surrounding Indian education; Kiranjot Singh will explain the concepts of punctum, negotiated reading and producer’s intended meaning;
One thing us humans have never been able to fully understand is astronomy. Always an unexplained mystery, astronomy also serves as a way to keep time and predict the future. The word “astronomy” is defined as the study of heavenly bodies, meaning anything in the sky such as stars, galaxies, comets, planets, nebulae, and so on. Many people, if not everyone, are amazed by the night sky on a clear, moonless night. Astronomy dates back to ancient times when peoples such as the Babylonians, Egyptians, and Chinese kept written records of astronomical events and occurrences.