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hw9 - WebCT Quiz Page 1 of 7 Homework#9 Name Leslie...

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Homework #9 Name: Leslie Looney (Preview) Number of Questions: 20 Finish Help Question 1: (5 points) The specific characteristics that identify most quasars are Question 2: (5 points) The extreme redshifts of quasar spectra are caused by Question 3: (5 points) What observations convince us that the energy source of a quasar is physically very small? n m l k j 1. that they look like elliptical galaxies, but with high spectral redshifts. n m l k j 2. bright, starlike appearance and very high spectral blueshift, indicating that they are approaching the Sun very fast, and rapid intensity fluctuations, indicating small intrinsic size. n m l k j 3. bright, starlike appearance with very high redshifts and hence very large distances, indicating very energetic sources. n m l k j 4. spiral galaxy appearance and very high spectral blueshift, indicating that they are coming toward the Sun at high speed. Save answer n m l k j 1. very high recession speeds of the sources away from our Galaxy. n m l k j 2. absorption of all but the red parts of the quasar spectrum by intergalactic matter. n m l k j 3. Zeeman effects from the very intense magnetic fields in the vicinity of the source. n m l k j 4. high gravitational fields at the surfaces of these quasars (gravitational redshift). Save answer n m l k j 1. Rapid fluctuations in brightness, since variations over one day mean that the source must be less than one light-day across. n m l k j 2. The instant disappearance of the quasar when occulted by the Moon's edge as the Moon moves in front of a quasar, indicating a very small source size. n m l k j 3. The sharpness of the emission lines in their optical spectra, since motions within a large Page 1 of 7 WebCT Quiz 09.Dec.03 https://webct.cites.uiuc.edu/SCRIPT/astro100_lwl/scripts/student/serve_new_quiz_show?...
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Question 4: (5 points) The surprising observational fact about quasars is that they appear Question 5: (5 points) Which of the following objects is NOT classified as an active galaxy? Question 6: (5 points) The mechanism that appears to generate two extensive regions of radio emission near active galaxies is source would smear out the line shapes. n m l k j 4. The extremely small size of the image of a quasar, even from Hubble Space Telescope images and radio interferometry measurements. Save answer n m l k j 1. to be the largest known structures in the universe, although they produce only modest amounts of energy. n m l k j 2. to produce the energy output of greater than 100 galaxies in a volume similar to that of our planetary system. n m l k j 3. to be associated with ancient supernova explosions. n m l k j 4. to be moving rapidly toward us, while emitting large amounts of energy. Save answer n m l k j 1. A Seyfert galaxy. n m l k j 2. A BL Lacertae object.
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