Supernova

=Supernova - //'Ends with a bang'//=

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A supernova is a star that explodes and becomes billions of times as bright as the sun before gradually vanishing. When the brightness of a supernova has reached its peak its brightness may outshine an entire galaxy. The explosion of the supernova throws a tremendous cloud of dust and gas into space. The mass of the excluded materials such as dust particles may go beyond the mass of the Sun!

In a standard year astronomers observe and see at least 20 supernovae. Astronomers estimate that one supernova occurs about every 30 years in a galaxy. But in our own galaxy, the Milky Way, only seven supernovae have been seen during the last 2,000 years this is due to the Milky Ways inner particles which is hidden by dust and gas. The Danish astronomer Tycho Brahe observed a Milky Way supernova in 1572. The Polish astronomer Johannes Kepler described the most recent supernova to be observed in our galaxy in 1604.

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There are 2 types of supernovae which astronomers recognize: supernovae--Type I and Type II.

Type I supernovae occur in binary ( double ) star systems. This is where one of the two stars is a small, dense star called a white dwarf star. The gravitational pull of the white dwarf attracts mass from the other star, which is larger than the white dwarf, which is also called a red giant. When the white dwarf reaches a mass about one and a half times that of the sun, it collapses and then explodes into a supernova.

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A Type II supernova results from the death of a single star much more massive and bigger than the sun both in size and weight. sun. When the star begins to burn out, its core quickly breaks down and becomes extremely hot and scortching. Nuclear reactions occur in the core, and a tremendous energy is suddenly released. Then the star erupts into a supernova which then explodes.

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This another imge of Type 2 supernova

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Most supernovae reach their maximum brightness a few days after they explode, and shine strongly for several weeks. Some supernovae fade within months while others fade over a period of years. Supernovae may also differ in the amount of material they force out and the structure of that material. Another difference between supernovae is in the type of object they leave behind. After some supernova explosions, a small, dense star made up of of neutrons remains. After other explosions, an invisible object called a black hole may be left behind. A black hole has such powerful gravitational force that not even light can escape it.

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Scientists believe that supernovae probably created many of the heavier elements that make up the earth and other objects of the solar system. These elements include carbon, gold, iron, oxygen, silicon, and uranium.

In 1054, Chinese astronomers observed a supernova so bright that it was visible during the day. It blew off a huge cloud of gas and dust that expanded and is still now visible as the [|Crab Nebula.]

In 1987, a Type II supernova became visible in a cloud which occured in a galaxy closest to the Milky Way. It was the brightest supernova observed in almost 400 years and the first since 1885 to be visible to the naked eye. It could be viewed only from the Southern Hemisphere.

This is what a supernova is.

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