ES 1010 Earth Science
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 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 source of their energy. They are all undergoing fusion of hydrogen into helium within their cores. The rate at which they do this and the amount of fuel available depends upon the mass 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 long periods of time. Any model of such stars must be able to account for their stability. Ninety percent of a stars life is in the main-sequence. A red giant is a luminous giant star of low intermediate mass that is in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius immense and the surface temperature low, somewhere from 5,000 K and lower. The appearance of the red giant is from yellow orange to red, including the spectral types K and M, but also class S stars and most carbon stars. The burnout and death final stage of a star depends on its mass. After a low mass star like the Sun exhausts
- 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 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 source of their energy. They are all undergoing fusion of hydrogen into helium within their cores. The rate at which they do this and the amount of fuel available depends upon the mass 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 long periods of time. Any model of such stars must be able to account for their stability. Ninety percent of a stars life is in the main-sequence. A red giant is a luminous giant star of low intermediate mass that is in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius immense and the surface temperature low, somewhere from 5,000 K and lower. The appearance of the red giant is from yellow orange to red, including the spectral types K and M, but also class S stars and most carbon stars. The burnout and death final stage of a star depends on its mass. After a low mass star like the Sun exhausts