Supernovas+-+BJ

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 * Written Information **: Supernovae(plural for supernova)are the final stages of a star's life.As a star continues in its life, it constantly burns off helium and other gases. When the gases are completely or mostly used up, the star will explode.The formations of the explosions are due to the amount of how much gas is in the star that exploded. The most common pictures of supernovas are not the explosions, but the remnants of the explosion. The remnants are the remains of the star( core, mantle, etc.). Due to that, supernovae emit high levels of radiation. The light of the spectacular formations only last for a few years. Only one supernova has ever been seen by the naked eye. That was Supernova 1987A, which occurred in 1987. Most supernovas are seen by X-ray telescopes. Two widely known supernovas are the Kepler remnants, which were discovered by Johannes Kepler,and the Crab Nebula,which actually resembles a crab.

Visuals Make sure to include the location of your image; add a caption with this information
 * || [[image:http://callisto.ggsrv.com/imgsrv/FastFetch/UBER1/00202996-T3 caption="This is the Kepler Supernova Remnants"]] ||   ||
 * || [[image:http://t3.gstatic.com/images?q=tbn:ANd9GcSbTHIoVvSlokyTfzeJbfw-Vk4TOHTUlyOafAE2fGS4gCkg1My7 width="252" height="200" caption="This spectacular supernova is only called the 1994D supernova"]] ||  ||
 * || [[image:http://tmsmawakasci4.wikispaces.com/site/embedthumbnail/placeholder?w=200&h=176 width="6" height="6"]] ||  ||

**Works Cited** **Sources**

http://en.wikipedia.org/wiki/Supernovas [] [] []
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**Topic: Supernovas**

**Notes**

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Supernova

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As stars age, many use up their fuel and fade away to oblivion. Others, however, go out with a bang as supernovae, releasing energies of up to 1044 joules--where one joule is equal to the amount of energy exerted by a force of one newton as it moves an object through a distance of one meter. Thus, such energies sent out by an average sized supernova is equivalent to around ten octillion (1028) times the power of a typical nuclear bomb. The energy released at the instant a supernova occurs is also equivalent to the total output of a typical star, such as the Sun, over its entire lifetime. The explosions of low-mass stars can be triggered by the accretion of mass from a companion star in a binary system to create classical, or Type Ia, supernovae. These supernovae show no hydrogen in their spectra. Massive stars, on the other hand, proceed through normal nuclear fusion but then, when their energy supply runs out, there is no outward pressure to hold them up and they rapidly collapse. The core is crushed into a neutron star or black hole, and the outer layers bounce and are then hurled outward into the surroundings at many million kilometers per hour. These are Type Ib and II supernovae. The Type II supernovae still eject some hydrogen from the unprocessed atmosphere of the star. During a supernova explosion, temperatures are so high that all the known elements can be produced by nuclear fusion.=====

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The most recent supernova ( Supernova 1987A) that was close enough to be seen without a telescope occurred in early 1987 within a nearby galaxy, the Large Magellanic Cloud. Also known as SN 1987A, it is the only supernova for which there is accurate data on the progenitor star before it exploded. It has been a tremendous help to astronomers in understanding how stars explode and expand.=====

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The only supernova to have been observed (and verified by astronomers) within the Milky Way galaxy is Supernova 1604 (SN 1604), which is located in the constellation Ophiuchus. SN 1604 is sometimes also called Kepler's Supernova because it was observed by German astronomer Johannes Kepler (1571-1630) on October 8, 1604. The supernova occurred about 20,000 light-years from the solar system.=====

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The rapidly growing surface of the star can brighten by up to one hundred billion times. Then, as the material gets diluted, it becomes transparent and the brightness fades on time scales of a few years. The ejecta are still moving rapidly, however, and quickly sweep up surrounding matter to form a shell that slows down as mass gets accumulated, an action similar to that of a snowplow. This is the beginning of the supernova remnant that can be visible for tens of thousands of years. SN 1987A is starting to show such interaction with its surroundings.=====

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Supernova remnants emit various forms of radiation. The material is moving highly supersonically and creates a shock wave ahead of it. The shock heats the material in the shell to temperatures over one million degrees, producing bright x rays. In the presence of interstellar magnetism, shocks also accelerate some electrons to almost the speed of light, to produce strong synchrotron radiation at radio wavelengths. Sometimes, even high-energy gamma rays can be produced. Dense areas can also cool quickly and astronomers observe filaments of cool gas, at about 10,000 kelvin (9,727�C, or 17,540�F), in various spectral lines at optical wavelengths.=====

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In AD 1054, astronomers in China and New Mexico observed a famous example of the explosion of a massive star: what is now called Supernova 1054 (SN 1054). What remains is a large volume of material that, with a lot of imagination, looks like a crab and, hence, is named the Crab Nebula. The object is being stimulated by jets from a rapidly spinning (about thirty times a second) neutron star called a pulsar. In most supernova remnants, the shell (discussed above) surrounds this pulsar wind nebula, but remarkably, no one has yet detected the shell around the Crab Nebula. Oppositely, the young supernova remnant Cassiopeia A has a shell and a neutron star but no pulsar wind nebula. Astronomers hope to explain these and many other mysteries about supernovae and their remnants using more multi-wavelength observations with new telescopes.=====

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Astronomers all over the world are learning much more about supernovae (or, supernovae) with the use of high-power space observatories. For instance, the National Aeronautics and Space Administration's (NASA's) Chandra X-ray Observatory (Chandra) is one very powerful instrument that is opening up hidden information about energetic astronomical objects in the universe, such as supernovae. Launched in July 1999 by a U.S. space shuttle, Chandra observes x-ray sources in the universe that were previously hidden from view. It does this by the high-angular resolution of its mirrors, which are able to image x-ray sources that are over one hundred times fainter than those viewed by past x-ray telescopes.=====

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Early on in its career, Chandra observed a never-before-observed ring around the central region of the Crab Nebula. In 2008, Chandra found the most recent supernova to have occurred in the Milky Way galaxy. The supernova remnant, what was left behind when the star exploded about one hundred forty years ago, is called G1.9+3. When it did explode many years ago, technology was not good enough to see it because it occurred within a dense volume of gas and dust near the center of the galaxy. However, Chandra was able to see through the "fog" using its sensitive x-ray and radio instruments.=====

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Future telescopic missions to observe supernovae and other energetic astronomical phenomena are now being planned. For instance, the International X-ray Observatory (IXO) is being developed as a joint space observatory program among NASA, the European Space Agency (ESA), and the Japan Aerospace Exploration Agency (JAXA). Its launch is planned for 2020.=====