Essay on ES 1010 Earth Science

851 Words Jan 23rd, 2015 4 Pages
ES 1010, Unit 8 Question 11
- Discuss stellar evolution (describing each stage in brief). What forces are opposing one another throughout the life of a star and how do they influence the various stages in the life cycle of a star Stellar evolution stars exist because of gravity. The two opposing forces in a star are gravity (contracts) and thermal nuclear energy (expands). Stage 1 Birth is where gravity contracts the cloud 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 formed about a million years after a gas clump from an interstellar gas cloud has started
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Hydrogen burning continues in a shell around the core and the star evolves into a red giant. When the Sun becomes a red giant, its atmosphere will envelope the Earth and our planet may be consumed in a fiery death. Meanwhile, the core of the star collapses under gravity's pull until it reaches a high enough density to start burning helium to carbon. The helium burning phase will last about 100 million years, until the helium is exhausted in the core and the 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 hot core of carbon embedded in a nebula of expelled gas. Radiation from this hot core will ionize the nebula, producing a striking "planetary nebula", much like the nebulae seen around the remnants of other stars. The carbon core will eventually cool and become a white dwarf, the dense dim remnant of a once bright star.

Reference
Lutgens, F. K. & Tarbuck, E. J. (2011). Foundations of earth science (6th ed.). Upper Saddle River, NJ: Prentice Hall

ES 1010, Unit 8, Question 12
- How do we calculate or determine 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

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