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Unformatted text preview: Homework Assignment 4 Answers PHYS 206: The Milky Way Inside and Out In the following multiple choice items, there may be one or more correct answers. 1. Stellar Magnitudes : (a) represent flux. (b) represent the mass of a star. (c) are logarithmic, so that the difference (subtracting one magnitude from another) represents the ratio of two values. (d) represent the temperature of the star. (e) represent the age of the star. 2. Color: (a) is represented as the difference between two magnitudes. (b) is represented as the ratio of two magnitudes. (c) is directly related to the stellar luminosity (d) is directly related to the stellar flux (e) is directly related to the stellar temperature (f) is directly related to stellar mass. 3. The Hertzsprung-Russell Diagram: (a) is a plot of stellar luminosity vs. effective temperature. (b) is a plot of stellar mass vs. age (c) when plotted as an optical color vs. magnitude, (d) revealed the existence of the main sequence of stars (e) was most significant for revealing the existence of the stellar main-sequence (f) aids our understanding of stellar evolution (g) demonstrates that stars are powered by nuclear fusion. 4. The stellar main-sequence: (a) exhibits the progression in luminosity and temperature of a single star as it loses mass (b) exhibits the progression in luminosity and temperature of a single star as it gains mass (c) exhibits the observed relationship between luminosity and temperature of stars of many different masses (d) exhibits the observed relationship of a single star as it evolves from being powered by nuclear fusion, through its giant and super-giant phases, toward a stellar endpoint. (e) includes proto-stars, dwarfs, giants, super-giants and white dwarfs. (f) includes only stars which are presently burning H. 5. Main-Sequence stars first form: (a) as neutron stars in supernovae (b) as white dwarfs following planetary nebulae (c) in molecular clouds, through gravitational collapse (d) as black holes in supernovae 6. All of a main sequence stars properties are fundamentally dependent on its: (a) age (b) luminosity (c) mass 1 (d) temperature (e) color (f) magnitude 7. Select the listings in which the stages and/or phenomena associated with a low-mass stars ( < 1.5 M ) evolution are in the correct chronological order: (a) white-dwarf, proto-star, main sequence, planetary nebula, giant (b) giant, main-sequence, planetary nebula, white dwarf, proto-star (c) proto-star, main-sequence star, giant, H-burning, planetary nebula, white dwarf (d) supernova, H-burning, proto-star, planetary nebula (e) proto-star, red dwarf, white dwarf, giant, super-giant, planetary nebula...
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