Earth Science Essay

Discuss stellar evolution (describing apiece stage in brief). What forces be opposing one another end-to-end the life of a head and how do they influence the various stages in the life cycle of a star Stellar evolution stars pull round beca usance of staidness. The two opposing forces in a star atomic number 18 gravity (contracts) and thermal nuclear energy (expands). Stage 1 Birth is where gravity contracts the dapple and the temperature rises, becoming a protostar. Protostars are a hypothetical cloud of dust and atoms in space which are believed to develop into a star. Astronomers are fairly certain of their existence. Protostars are make about a million years after a botch up clump from an interstellar gas cloud has started to rotate and from a disk. The protostar is simply the core of the disk that formed from the clump of gas that was compressed inside the gas cloud. The star becomes a stable main-sequence star, which are characterized by the rootage of their energy .They are alone undergoing federation of hydrogen into helium within their cores. The rate at which they do this and the measuring stick of fuel available depends upon the bunch of the star. Mass is the key factor in determining the lifespan of a main sequence star, its size and its luminosity. Stars on the main sequence also appear to be unchanging for desire periods of time. Any model of such stars must be able to identify for their stability. Ninety percent of a stars life is in the main-sequence. A departure giant is a luminous giant star of low mean(a) mass that is in a late material body of stellar evolution. The out atmosphere is inflated and tenuous, making the radius immense and the surface temperature low, someplace from 5,000 K and lower. The appearance of the red giant is from yellow orange to red, including the ghostlike types K and M, but also class S stars and most carbon paper stars. The burnout and death final stage of a star depends on its mass. afterw ards a low mass star like the solarise exhausts the tot of hydrogen in its core, there is no longer any source of heat to support the core against gravity. Hydrogen burning continues in a shell around the core and the star evolves into a red giant. When the sunlight becomes a red giant, its atmosphere will envelope the Earth and our major planet may be consumed in a fiery death. Meanwhile, the core of the star collapses under gravitys pull until it reaches a high decent density to start burning helium to carbon.The helium burning material body will last about 100 million years, until the helium is purpose slight in the core andthe star becomes a red supergiant. At this stage, the Sun will have an outer envelope extending out towards Jupiter. During this brief phase of its existence, which lasts only a few tens of thousands of years, the Sun will lose mass in a powerful wind. Eventually, the Sun will lose all of the mass in its envelope and leave behind a piquant core of carbo n embedded in a nebula of expelled gas. Radiation from this sweltering core will ionize the nebula, producing a striking planetary nebula, more like the nebulae seen around the footprints of other stars. The carbon core will ultimately cool and become a white dwarf, the dense dim remnant of a once bright star.ReferenceLutgens, F. K. & Tarbuck, E. J. (2011). Foundations of earth science (6th ed.). pep pill Saddle River, NJ Prentice HallES 1010, Unit 8, interrogatory 12 How do we calculate or gibe the distances to stars? What units do we use and what are the limitations (if any) of the method used for such calculations? Measuring distance to stars has been considered a very difficult task. Stellar parallax is a method used to determine distance, the extremely back and forth shifting in a near stars apparent position due to the orbiting motion of earth. The farther away a star is, the less its parallax. The light year is a unit used to express stellar distance, which is the di stance light travels in a year, which is approximately 9.5 trillion kilometers (5.8 trillion miles). The parallax pitchs are very small. Proxima Centauri is the parallax angle nearest to the star.It is less than one second or arc, which equals 1/3600 of a degree. A human finger is roughly 1 degree wide. The distances to stars are so large that conventional units such as kilometers or astronomic units are often too cumbersome to use. Some limitations are that parallax angles of less than 0.001 arcsec are very difficult to measure from Earth because of the effects on the Earths atmosphere. This limits Earth based telescopes to measuring the distances to stars about 10.01 or 100 parsecs away. Spaced based telescopes can get accuracy to 0.001, which has increase the number of stars whose distance could be measured with this method. However, most stars even in our own galaxy are much further away than megabyte parsecs, sincethe Milky Way is about 30,000 parsecs across.ReferenceLutgens , F. K. & Tarbuck, E. J. (2011). Foundations of earth science (6th ed.). amphetamine Saddle River, NJ Prentice Hall