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20 Cards in this Set
- Front
- Back
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What is the diameter of the disk of the Milky Way? 10,000 light-years 100,000 light-years 1,000,000 light-years 1,000 light-years 100 light-years |
100,000 light-years |
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What kinds of objects lie in the halo of our galaxy? gas and dust open clusters globular clusters O and B stars all of the above |
globular clusters |
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What kinds of objects lie in the disk of our galaxy? old K and M stars gas and dustO and B stars open clusters all of the above |
all of the above |
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What makes up the interstellar medium? open clusters gas and dust O and B stars K and M stars all of the above |
gas and dust |
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How does the interstellar medium obscure our view of most of the galaxy? It produces so much visible light that it is opaque and blocks our view of anything beyond it. It reflects most light from far distances of the galaxy away from our line of sight. It absorbs visible, ultraviolet, and some infrared light. It absorbs all wavelengths of light. all of the above |
It absorbs visible, ultraviolet, and some infrared light. |
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Harlow Shapley concluded that the Sun was not in the center of the Milky Way Galaxy by mapping the distribution of stars in the galaxy. mapping the distribution of globular clusters in the galaxy. mapping the distribution of gas clouds in the spiral arms. looking at other nearby spiral galaxies. looking at the shape of the "milky band" across the sky. |
mapping the distribution of globular clusters in the galaxy. |
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Approximately how far is the Sun from the center of the galaxy? 28 light-years 28 million light-years 28,000 light-years 280 light-years 2,800 light-years |
28,000 light-years |
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What do astronomers consider heavy elements? elements that are heavier than carbon elements that are heavier than uranium elements that are heavier than iron elements that are heavier than hydrogen all elements besides hydrogen and helium |
all elements besides hydrogen and helium |
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Where are most heavy elements made? in the Big Band, when the universe first began in the interstellar medium in stars and supernovae none of the above all of the above |
in stars and supernovae |
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How are interstellar bubbles made? by the rapidly rotating magnetic fields of pulsars by the collapse of a gas cloud to form stars by collisions between galaxies by planetary nebulae from low-mass stars by the winds of massive stars and supernovae |
by the winds of massive stars and supernovae |
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What can cause a galactic fountain? the combined effect of spiral density waves a supernova occurring in the halo molecular clouds falling towards the galactic center winds and jets from newly-formed protostars multiple supernovae occurring together |
multiple supernovae occurring together |
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What produces the 21-cm line that we use to map out the Milky Way Galaxy? molecular hydrogen helium ionized hydrogen atomic hydrogen carbon monoxide |
atomic hydrogen |
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Compared with our Sun, most stars in the halo are young, blue, and bright and have much more heavy element material old, red, and dim and have much more heavy element material old, red, and bright and have fewer heavy elements young, red, and dim and have fewer heavy elements old, red, and dim and have fewer heavy elements |
old, red, and dim and have fewer heavy elements
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Compared with stars in the disk, orbits of stars in the halo are relatively uniform to each other. are elliptical, with random orientation. do not have to be around the galactic center. do not have to pass through the plane of the galaxy. are elliptical but orbiting in the same direction. |
are elliptical, with random orientation. |
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Where does most star formation occur in the Milky Way today? in the spiral arms uniformly throughout the Galaxy in the bulge in the Galactic center in the halo |
in the spiral arms |
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Which constellation lies in the direction toward the galactic center? the Big Dipper Orion Leo Sagittarius Taurus |
Sagittarius |
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How do we learn about what is going on in the center of our own galaxy (the Milky Way)? We cannot see the galactic center with visible or ultraviolet light, but radio and X rays from the center can be detected. We have learned it only recently, thanks to the great photographs obtained by the Hubble Space Telescope. We must look at the centers of other galaxies and hope that ours is just like others. The gas and dust in the Milky Way prevent any type of direct observation of the galactic center, but theoretical models allow us to predict what is happening there. |
We cannot see the galactic center with visible or ultraviolet light, but radio and X rays from the center can be detected. |
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Which of the following does not accurately describe what we observe toward the Galactic center? at X rays, we see faint emission from an accretion disk around a black hole at optical wavelengths, we see a cluster of old, red stars at radio wavelengths, we see giant gas clouds threaded by powerful magnetic fields at infrared wavelengths, we see a massive stellar cluster |
at optical wavelengths, we see a cluster of old, red stars |
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What evidence supports the theory that there is a black hole at the center of our galaxy? We can see gas falling into an accretion disk and central mass at the center of our galaxy. We observe an extremely bright X-ray source at the center of our galaxy. The motions of the gas and stars at the center indicate that it contains a million solar masses within a region only about 1 parsec across. We observe a large, dark object that absorbs all light at the center of our galaxy. all of the above. |
The motions of the gas and stars at the center indicate that it contains a million solar masses within a region only about 1 parsec across. |
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What is Sgr A*? a source of bright X-ray emission coming from the entire constellation of Sagittarius the brightest star in the constellation Sagittarius a source of bright radio emission in the center of our galaxy the bulge at the center of our galaxy a source that is bright in the visible wavelengths in the center of our galaxy |
a source of bright radio emission in the center of our galaxy |
