This paper focuses on a supernova and its occurrence. It describes how it occurs an also some of the supernovae that has occurred in the past. Lastly, this paper focuses on Crab Nebula, which is one of the supernovae. It creates the understanding of the science behind supernova and concludes by highlighting its influence to the environment.
Supernova refers to a stellar explosion which produces more energy than a nova (Parker 12-23). It is extremely luminous, and it usually causes a burst of radiation which significantly outshines the entire galaxy. It then fades from viewing after several weeks or even months. During this interval, a supernova is a capable of producing as much energy as that the sun can produce on its expected life span (Parker 12-23). In addition, the explosion usually expels much or even all of the materials of the star at a velocity of 300000 kilometers per second. During this explosion, it drives a shock wave into the interstellar medium surrounding it. The shock wave then sweeps up the expanding gas shell as well as dust referred to as supernova remnant (Marschal 2-4).
A supernova explosion releases a substantial amount of radio waves as well as X-rays. In addition, it also releases cosmic rays (Parker 12-23). A supernova explosion also releases majority of the heavy elements which make up the constituents of the solar system into the interstellar medium. A reliable research indicates that abundance of these heavy elements is greater than normal (Marschal 2-4). This implies that these elements do not form during the explosion as many may tend to argue. The supernova remnant shell continues to expand significantly until at an advanced age, where it then dissolves completely into the interstellar medium.
The recent supernova was observed in 1987 by a Canadian astronomer while working at Campanas observatory in Chile. This supernova attained magnitude of 4.5 in just after few hours, making it visible with naked eyes (Parker 12-23).
There are two broad categories of supernovae. These are Type I and Type II. This classification is according to what they detonate (Parker 12-23). A type I supernova is usually three times brighter than a Type II supernova. In addition, unlike Type II, Type I contains no hydrogen lines and they usually expand about twice as rapidly as Type II. Type I supernova results from binary systems in which a white dwarf of carbon-oxygen becomes an accreting matter from a companion (Marschal 2-4).
Type II supernova, on the other hand, usually occurs at the end of a massive star lifetime, when its nuclear fuel becomes exhausted. This implies that it becomes no longer supported by the production of nuclear energy. If the star' core is massive enough, it will then collapse to become a Type II supernova (Parker 12-23). Before the 17th century, the number of recorded supernovae was only seven. One of the most famous supernovae is the Crab Nebula, whose remnants are still visible today.
Crab Nebula
The Crab Nebula is a supernova remnant as well as a pulsar wind nebula which is in the constellation of Taurus (Marschal 2-4). Observed in 1731 by John Bevis, the Crab Nebula corresponds to a supernova recorded by Chinese, Japanese and Arab astronomers in 1054, with energies levels of X-rays and gamma rays above 30 keV. The Crab is basically the strongest constant source in the sky. At the remnant of the core of the stellar progenitor is the heart of the nebula (Chevillard, E-ric, Jordan, & Eleanor 14-21). The mass of this neutron star is twice that of the Sun. This gives it a density of 109 per cm3. The nebula now usually acts as a source of radiation for the purpose of studying celestial bodies, which occur to it.
During visible light, the Crab Nebula constitutes of oval-shaped mass of filaments which surrounds a diffuse a central region (Chevillard, E-ric, Jordan, & Eleanor 14-21). These filaments are the remnants of the atmosphere of the progenitor star and consist mainly of hydrogen as well as ionized helium. In addition, it also consists of other elements including nitrogen, iron, neon, oxygen and sulphur.
Despite the fact that Crab Nebula is one of the major focuses among many astronomers all over the world, its distance is not clear, and this makes it remain an open question (Chevillard, E-ric, Jordan, & Eleanor 14-21). This is because there are a lot of uncertainties in all the methods used to determine its distance. Images taken in several years indicate that there is a slow expansion of the Nebula. This is evident through comparison of its angular expansion in various years.
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