esssay - Supernovae A supernova is an explosion caused by...

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SupernovaeA supernova is an explosion caused by the death of a star and is the primary source of heavy elements in the universe. There are two major types of supernovae, labeled Type I and Type II. "A Type I supernova occurs when a star accumulates matterfrom a nearby neighbor until a nuclear reaction ignites. A type II supernova occurs whena star runs out of nuclear fuel and collapses under its own gravity". (1)Originally, by observation, supernovae were classified by their spectra. Type I had no Hydrogen emission lines, while Type II did. It was later realized that “there were in fact three quite distinct type I supernovae, now labelled Type Ia, Type Ib and Type Ic.Type II supernovae are better understood, and so we will discuss them first. “Fora star to explode as a Type II supernova, it must be at several times more massive than the sun (estimates run from eight to 15 solar masses)” (1). These stars are seen in spiral galaxies, most often near the arms. We know that “until this stage of its evolution, the star has shone by means of thenuclear energy released at and near its core in the process of squeezing and heating lighter elements such as hydrogen or helium…in the process of nuclear fusion” (8). Once the star can no longer sustain energy by fusion of hydrogen and helium, it fuses heavier elements. Gradually, “the heavier elements build up at the center and it becomes layered like an onion, with elements becoming lighter towards the outside of the star” (1). If the mass of the star is great enough, eventually the iron core will reach the Chandrasekhar Mass which is about 1.4 times the mass of the Sun. When a star is this massive, electron degeneracy pressure is not enough to support it. Within an
instant, “the electrons disappear by combining with protons to form neutrons, releasing

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Term
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Tags
Astronomy, Nebulae, Supernovas, Stars, Death Of Star, Supernova, White dwarf, Bennett

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