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Unformatted text preview: Homework Assignment 3 Solutions. PHYS 206: The Milky Way Inside and Out In the following multiple choice items, there may be one or more correct answers. 1. The atmosphere will transmit at least 50% of the intensity of light in the following wavebands, which permits them to be observed from the ground: (a) gamma-rays (b) X-rays (c) ultra-violet (d) optical (e) (some) infra-red (f) radio 2. The atmosphere is largely opaque in the following wavebands, which means they cannot be observed from the ground, requiring space-based observations: (a) gamma-rays (b) X-rays (c) ultra-violet (d) optical (e) (some) infra-red (f) radio 3. The spectrum of the sun in the optical passband: (a) is thermal, and does not contain any emission or absorption lines (b) is thermal, and contains many absorption lines (c) is a pure emission line spectrum (d) is composed of only a single emission line which is the color of the sun (red/orange). 4. Some things learned from observing the spectrum of the sun include: (a) that the sun is pure hydrogen, which glows yellow in emission lines (b) that the sun is mostly hydrogen, with a large amount of Fe which gives it its reddish color (c) that the sun is mostly hydrogen, with some helium, and trace amounts ( < 1% each ) of different metals. (d) that there exists the element Helium since it was first observed in the solar spectrum before it was found on earth. (e) that the distant stars were probably very similar to our sun, since their spectra were very similar to that of our sun. 5. The light from the sun is powered by: (a) neutrino emission from the core of the sun; (b) the hot (2,000,000 K) solar corona (c) nuclear fission in the core of the sun (d) nuclear fusion in the core of the sun (e) burning (combining with oxygen) of the carbon on the surface of the sun, just as the carbon in wood burns. 1 6. Nuclear fission: (a) was discovered by Marie and Pierre Curie. (b) is the breaking apart of a heavy nucleus into lighter nuclei (c) takes place at very high density and temperature (d) takes place spontaneously (e) is the process (specifically, the fission process known as the proton-proton chain) which powers the sun (f) is the combining of two light nuclei into a heavier nucleus (g) is the process which takes place in a nuclear reactor 7. Nuclear fusion: (a) was discovered by Marie and Pierre Curie.(a) was discovered by Marie and Pierre Curie....
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