Life Cycle of Stars - Essay Example

Life Cycle of Stars The shining twinkle-twinkle little or big stars are all composed of enormous clouds of dust and gas. Stars too have a life of their own. These formations appear as twinkling to us because they are at a far off place from our earth and the atmospheric conditions, diffractions etc. lead to the phenomenon of twinkling. Light is actually an electromagnetic wave that can be 'seen' by us. Initially there was much discussion over whether light is composed of particles or waves. Subsequent experiment proved that Light displays a dual nature1. While on the one hand particles are supposed to have some mass which can respond to forces (acceleration) waves can transfer energy from one place to another. The Corpuscular theory of Newton proved in 1670 that light corpuscles have mass and travel at extremely high speeds in straight lines, obeying the laws of reflection and dispersion. While the Huygens principles proved that light was composed of longitudinal waves like sound. Subsequent experiments also proved that light waves do produce diffraction and interference. Taking an aesthetic view on light, we can very say that had there been no light, life would not have been possible on earth. While Sun is the brightest star for us as it is the source of light for us, there are many more such stars, equally or more bright, but their light doesn't reach us in equal measure because they are situated at a distance of many more light years from us, for example 'Bullet Star' is said to shine 350 times brighter than the sun2. In fact the amount of information that is available in the depth of universe remains largely unexplored and astronomers are still on the lookout for more. Stars are an integral part of the Universe system. Other components of universe include planets, black holes, galaxies etc. Universe is everything that we can perceive and much more that is beyond our perception. Astronomers predict that there are zillions of stars in the universe. Some of them are red stars, some yellow stars while some other are known as blue giant stars. Their life time varies from millions of years to trillions of years. Small red stars are the one's burning their energy very slowly and are very cool. Therefore their lifetimes goes upto trillions of years, after which these stars end up as heavy little cinders. Yellow stars, like the sun, take billions of years before becoming white dwarf stars. Blue stars, also known as giant stars, burn their fuel fiercely and after millions of years end up their life with a loud explosion. The amount of energy release during the fuel burning process can be estimated from the fact that, when nuclear scientists undertake controlled fusion process; it results in an atom bomb. Stars are like giant nuclear reactors. In fusion, many nuclei combine together to form a larger one. In the process lot of energy is released, that's why stars appear as bright objects and emit much of their energy as visible light. Birth of Star: Stars are born with the help of huge clouds of gaseous elements and dust particles available in the outer space. This space dust and cloud, consisting of hydrogen and helium, is also known as Nebulae. When these clouds of dust and gas collapse under heavy gravitational pull, the temperature inside the formation starts rising. Gradually the temperature levels reach to several thousand degrees. Thereafter the hydrogen molecules start ionizing. In the process these molecules become single protons, as the electrons escape from them. This leads to the formation of a young star called protostar. Growth of star: The rise in temperature inside the star continues with further contraction of gases. And when the temperature reaches a level of about 10,000,000 degrees Celsius (18,000,000 degrees Fahrenheit), nuclear fusion starts. At this point, the protostar becomes a full fledged star and becomes a part of the main sequence of the universe. Depending upon the process of fusion, ferocity of heat generation and the surface brightness stars can further be classified as; Red Stars: Stars which have smaller size and continue to burn their energies very slowly, are known as cool stars or red stars. These stars have the longest lifespan measured in trillions of years. Yellow Star: These stars are bigger than red stars in size. They release much higher energy and light, as the process of fusion is more in these stars. These stars are hot stars. Sun is one example of such a star. The life span of these stars is billions of years. Blue Star: These are the ultimate stars, known as giant stars or blue stars. These stars are the hottest and brightest stars in universe. These stars finish their lifetimes rapidly as compared to the other two categories, as they burn their fuel much more fiercely through the process of fusion. Their lifespan is about couple of million of years. Death of Star: After spending most of their life battling against the gravitational forces, stars decimate to once again become dense clouds. When the star continues to burn the hydrogen for the fusion process, gradually the hydrogen supply starts depleting and a time comes when the hydrogen supply is totally exhausted. Even before the exhaust of the hydrogen supply a phase comes in the life of a star when it starts swelling and its outer region starts becoming red in color. Because the surface starts expanding, the star's outer shell becomes comparatively cooler. Such a swollen star is then called a red giant. Red giant is a short phase in the lifecycle of a star. Each star has to undergo through this process and sun will also become a red giant when it exhausts its lifespan. At the moment sun is said to be middle aged star and it is predicted to become a red giant in the next 5 billion years. Thereafter, the sun's outer surface will become comparatively cooler, but since its size will become more, the distance between earth and sun will start reducing. This in turn will start the process of vaporizing Earth and all creatures on its surface. When all the fuel of star is exhausted, it cannot generate sufficient pressure at its centre to balance the high force of gravity. Therefore the gravitational force starts attracting everything from the outer surface towards the centre. The star starts collapsing under its own weight. If it is a smaller star, like red star (not red giant), then it end into a white dwarf or a dwarf star. If it is a middle size star, like the sun, then it ends up in heavy little pieces like charred wood or coal called cinders. But when the star is larger in size i.e. a like a giant blue star then it doesn't end its life silently. Its death follows a supernova, a violent explosion, resulting in blowing off the pieces of star in different directions. These pieces thereafter become part of other stars, from where a new beginning is made. References: 1. Science Daily (2005). Astronomers: 'Bullet Star' Shines 350 Times Brighter Than The Sun. available online at; http://www.sciencedaily.com/releases/2005/01/050121092523.htm (July 11, 2007) 2. Life Cycle of Stars. Available online at http://www.airynothing.com/high_energy_tutorial/basic_astro/life_cycle.html 3. Birth and Death of a Star. Available online at; http://www.infoplease.com/ipa/A0004429.html 4. MacRobert, Alan M. The Spectral Types of Stars. Available online at. http://www.skyandtelescope.com/howto/basics/3305876.html (July 12, 2007) Read More