Supernova
Supernova->> FORMATION OF A SUPERNOVA
The mass of a star determines whether it will end its life in a supernova explosion. During the courses of their lifetimes, all stars convert hydrogen to helium in thermonuclear fusion reactions in their cores. Thermonuclear fusion reactions occur when the intense heat and gravitational force in a star’s nucleus force hydrogen atoms together. The atoms merge, or fuse together, creating helium atoms and releasing large amounts of energy in the form of electromagnetic radiation and heat. Massive stars have faster rates of fusion than smaller stars, so large stars may use up their fuel faster. After most of the hydrogen is used up, a star goes into a carbon-building phase, in which nuclear fusion turns the helium into carbon. After the helium is exhausted, most stars gradually cool until they no longer emit radiation.
When a star eight or ten times more massive than the Sun exhausts its helium, however, the nuclear burning cycle is far from complete. In these stars, the carbon core shrinks under its own weight, and its temperature rises high enough to fuse carbon into oxygen, neon, silicon, sulfur, and finally, iron.
Iron is the most stable element formed in stars, and even the intense heat and pressure of a stellar nucleus cannot force iron atoms to fuse into heavier elements. The thermonuclear process at the star’s core is essentially complete. At this point, the outward pressure produced by the reactions can no longer balance the inward gravitational attraction between atoms. As a result, all the core can do is collapse under its own weight. As it does so, the star implodes, transforming gravitational energy into kinetic energy, or energy of motion. The core of the star collapses in on itself, but as it does so, it transfers to the star’s atmosphere kinetic energy that sends the atmosphere exploding outward from the star’s core. The particles of the star’s atmosphere begin moving rapidly away from the star, tearing apart the star’s atmosphere.
Astronomers know of several variations of supernovas, but they all fall into one of two main types. The two kinds of supernovas are called Type I and Type II and are differentiated mostly by the presence of hydrogen in their debris. Type I supernovas tend to be older stars that have completely exhausted their hydrogen. Type II supernovas come from younger stars that have used up the hydrogen in their nucleus but have large amounts of hydrogen in their atmospheres. Astronomers can measure what elements exist in a star by examining its light because atoms of different elements emit and absorb electromagnetic radiation at different wavelengths. By separating a star’s light into its wavelengths, astronomers can tell which wavelengths are missing or especially bright, and therefore what elements are present in the star.
The mass of a star determines whether it will end its life in a supernova explosion. During the courses of their lifetimes, all stars convert hydrogen to helium in thermonuclear fusion reactions in their cores. Thermonuclear fusion reactions occur when the intense heat and gravitational force in a star’s nucleus force hydrogen atoms together. The atoms merge, or fuse together, creating helium atoms and releasing large amounts of energy in the form of electromagnetic radiation and heat. Massive stars have faster rates of fusion than smaller stars, so large stars may use up their fuel faster. After most of the hydrogen is used up, a star goes into a carbon-building phase, in which nuclear fusion turns the helium into carbon. After the helium is exhausted, most stars gradually cool until they no longer emit radiation.
When a star eight or ten times more massive than the Sun exhausts its helium, however, the nuclear burning cycle is far from complete. In these stars, the carbon core shrinks under its own weight, and its temperature rises high enough to fuse carbon into oxygen, neon, silicon, sulfur, and finally, iron.
Iron is the most stable element formed in stars, and even the intense heat and pressure of a stellar nucleus cannot force iron atoms to fuse into heavier elements. The thermonuclear process at the star’s core is essentially complete. At this point, the outward pressure produced by the reactions can no longer balance the inward gravitational attraction between atoms. As a result, all the core can do is collapse under its own weight. As it does so, the star implodes, transforming gravitational energy into kinetic energy, or energy of motion. The core of the star collapses in on itself, but as it does so, it transfers to the star’s atmosphere kinetic energy that sends the atmosphere exploding outward from the star’s core. The particles of the star’s atmosphere begin moving rapidly away from the star, tearing apart the star’s atmosphere.
Astronomers know of several variations of supernovas, but they all fall into one of two main types. The two kinds of supernovas are called Type I and Type II and are differentiated mostly by the presence of hydrogen in their debris. Type I supernovas tend to be older stars that have completely exhausted their hydrogen. Type II supernovas come from younger stars that have used up the hydrogen in their nucleus but have large amounts of hydrogen in their atmospheres. Astronomers can measure what elements exist in a star by examining its light because atoms of different elements emit and absorb electromagnetic radiation at different wavelengths. By separating a star’s light into its wavelengths, astronomers can tell which wavelengths are missing or especially bright, and therefore what elements are present in the star.
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