Astronomy Essay Example | Topics and Well Written Essays - 750 words

Astronomy - Essay Example 4). Explain how type I and Type II. Supernovae occur. 1). The four main grouping of stars as depicted by the Hertzprung- Russel diagram are dwarf (white and red) stars, main sequence grouping stars, giant stars and supergiant stars (p. 142). The white dwarf stars are Sirius B, Wolf 486, Van Maanen's star, Procyon B, Wolf 1346 and 40 Eridani B. The size characteristic of these stars is ranging from 0.008 R to 0.03 R. The stars in the white dwarf category have temperatures ranging from 5,000 K to 25, 000 K. In between the white dwarf stars and the main sequence grouping we have Bernard's star. Bernard's star is a red dwarf. It has a radius of about 0.1 R and 150 L/L. Bernard's star is also the coolest star with temperatures of 2900 K. The white and red dwarf stars have Mv > 15. The main sequence stars are Aldebaran B, Alpha Centauri B, the Sun, Altair, Sirius, Procyon A, Vega, Rigel B, Pollux, Spica B, Spica A, Adara and Capella B. The luminosity class of these stars is V. The size of these stars vary from 1R to 10R. The stars in the main sequence grouping vary from 7,000 L/L to 85,000 L/L. The main sequence grouping stars have temperatures ranging from 3700 K for Aldebaran B to 30,000 K for Adara. The main sequence stars have between 5- 10 Mv. The next sequence of stars are the giants. Included in the giant classification of stars are Capella A, Aldebaran A, Arcturus, Mira and Canopus. The giant classification of stars have radii which vary from 10 R to 100 R. The luminosity class of the giant stars are III. The giant stars have a Mv between 0- 5. The next sequence is the supergiant sequence of stars. This includes Polaris, Deneb, Rigel A and Alnilam. The supergiants temperatures range from 10,000 K to 30,000K. The luminosity class is Ib. The largest stars are Betegeuse and Antares,.Betelgeuse has a size of 1000 R. Antares has a size of about 2000 R. The Mv for these stars is – 5 (p. 143). 2). A star is born from the thin gases of space. When a star is bo rn, there is normally a large cloud of gas and dust. The thin gases of space are known as the interstellar medium ( p. 162). When enough hydrogen is compressed through the gravity of these stars, hydrogen fusion is achieved. In the center core of these stars there is a helium core. A teaspoon of mass of helium from the center of a star would weigh more than a ton. When enough helium is compressed in the center of the star, there is an abrupt explosion of intense magnitude called a helium flash. For this particular moment in time, the center of the newly born star produces more energy per second than an entire grouping of stars. This helium flash causes the center of the star to increase in temperature, whereas a great number of electrons become excited by the reaction. This causes the hydrogen to fuse into helium. At that point, the star is born with a self sustaining hydrogen fusion reaction at its shell. Often there is a helium fusion reaction at the center of the star. The size o f the star is of the utmost importance, stars less than 0.40 solar masses never get enough energy to continue the helium fusion reaction process. Stars which are greater than 3 solar masses experience degeneration at their core before this phenomenon occurs (p. 187). In the star there are two types of fusion reactions, helium fusion at the center and hydrogen fusion at the shell. 3). A star begins to die when the helium fusion which occurs at its center begins to produce carbon, oxygen and neon. As the fusion