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1 | |
Modern optical telescopes |
| | A) | utilize huge, finely ground lenses that can be up to 5 meters in diameter. |
| | B) | if not adequately adjusted, will produce distorted images from the huge lenses that can sag under their own weight. |
| | C) | use concave mirrors instead of lenses. |
| | D) | tend to give better results when the stars are twinkling, indicating the atmosphere is perfectly still and clear. |
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2 | |
Which of the following is not an advantage of very large telescopes? |
| | A) | Magnification of the most faint stars so that they appear bigger than simple points of light. |
| | B) | The ability to resolve small details on certain astronomical objects, such as planets. |
| | C) | The ability to collect more light that can be used for analysis (such as spectrographic analysis) of previous known objects. |
| | D) | The ability to detect very faint objects that cannot be seen otherwise. |
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3 | |
Analyzing the spectra of stars, the hottest stars are |
| | A) | red. |
| | B) | orange-yellow. |
| | C) | blue-white. |
| | D) | there is no correlation between star color and temperature. |
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4 | |
The Zeeman effect |
| | A) | allows the relative motion of stars to be detected. |
| | B) | allows magnetic fields among stars and matter in space to be detected. |
| | C) | is useful in determining the chemical composition of stars. |
| | D) | provides the theoretical basis for determining the temperatures of stars based on their spectra. |
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5 | |
Our sun |
| | A) | is a fairly average and typical star. |
| | B) | in terms of mass, is composed primarily of hydrogen and helium. |
| | C) | has a volume so large that it could hold over a million earths. |
| | D) | all of the above are true. |
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6 | |
Which of the following is not a phenomenon found above and beyond the photosphere of the sun? |
| | A) | prominences |
| | B) | sunspots |
| | C) | the corona |
| | D) | the solar wind |
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7 | |
Airglow |
| | A) | is associated with the aurora borealis but not the aurora australis. |
| | B) | is due to human-made and volcanic pollutants in the lower atmosphere. |
| | C) | is due to diffuse streams of solar particles interacting with the upper atmosphere. |
| | D) | is due to micrometeorites burning up as they enter the atomosphere. |
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8 | |
Sunspots may have temperatures around |
| | A) | 500 K. |
| | B) | 5,000 K. |
| | C) | 50,000 K. |
| | D) | 500,000 K. |
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9 | |
Sunspot cycles |
| | A) | are correlated with changes in the energy output of the sun. |
| | B) | did not have any noticeable effect on earth-based phenomena before the invention of modern electronic equipment. |
| | C) | do not affect the intensity of the aurora as seen on the earth. |
| | D) | increased dramatically in number and intensity during the late 1600s, leading to the "Little Ice Age". |
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10 | |
In the interior of the sun |
| | A) | atoms can maintain their electrons, but they are unable to form compounds. |
| | B) | the density of matter is thought to be almost ten times that of lead on the earth. |
| | C) | the estimate temperature is 2 million K. |
| | D) | free electrons cannot exist as they are quickly annihilated by positrons. |
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11 | |
Most stars give off energy |
| | A) | by nuclear fission or elements heavier than carbon. |
| | B) | by the proton cycle or the carbon cycle. |
| | C) | drawing it from the virtual vacuum through a black hole. |
| | D) | by burning hydrogen and giving off water vapor. |
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12 | |
Parallax |
| | A) | could not be detected in any stars, due to their extraordinary distance from the earth, until modern telescopes were built in the late twentieth century. |
| | B) | is the apparent shift of an object as the observer moves. |
| | C) | can be calibrated in terms of light years. |
| | D) | all of the above are true. |
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13 | |
The differences between the intrinsic and apparent brightnesses of a star can be expressed as |
| | A) | mass versus volume. |
| | B) | temperature versus color. |
| | C) | total energy given off versus brightness seen from the earth. |
| | D) | age versus spectral spread. |
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14 | |
Cepheid variable stars are valuable to astronomers because |
| | A) | they are the only stars that are known to have planets orbiting them. |
| | B) | they came in lots of different colors and contain a diversity of elements, thus giving a good sample of the universe. |
| | C) | they can be used to find the distance to the star groups in which they were found. |
| | D) | they emit natural radio signals that can be employed in interstellar navigation. |
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15 | |
The relative positions of the stars in the night sky |
| | A) | are absolutely fixed and therefore we can name constellations with certainty. |
| | B) | change appreciably over about four thousand years, which is why the ancient. Egyptians named different constellations than those of today. |
| | C) | are changing, but very slowly such that appreciable change cannot be observed even over several centuries or even several thousand years. |
| | D) | appear to change because the sun moves among them over the course of a year. |
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16 | |
The temperature of a star can be found from its |
| | A) | spectrum. |
| | B) | position in a galaxy. |
| | C) | apparent brightness. |
| | D) | doppler shift compared to the apparent brightness. |
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17 | |
The color of the hottest stars is |
| | A) | blue-white. |
| | B) | yellow. |
| | C) | blue. |
| | D) | red. |
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18 | |
The reason stars less than one-fortieth as massive as the sun are not found is that |
| | A) | the internal fission reactions use up all the fuel very quickly. |
| | B) | they are so small that they fall into black holes. |
| | C) | the gravitational forces in such a small star would not hold it together against the pressure produced by the nuclear reactions in its interior. |
| | D) | gravity cannot squeeze the matter sufficiently to produce the temperatures necessary for nuclear fusion reactions. |
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19 | |
The Hertzsprung-Russell Diagram |
| | A) | is based on the principle that the intrinsic brightnesses of most stars are related to their temperatures. |
| | B) | most stars have the same temperature. |
| | C) | was developed in the 1950s by two American astronomers working for NASA. |
| | D) | while of great utility for most large stars, has proven of little value in classifying small stars like our sun. |
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20 | |
The main sequence on the H-R diagram includes |
| | A) | about 90 percent of all stars. |
| | B) | white dwarfs. |
| | C) | red giants. |
| | D) | pulsars. |
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21 | |
Stars are believed to originate |
| | A) | in clouds composed largely of hydrogen gas. |
| | B) | when black holes eject excess matter and energy. |
| | C) | when a supernova explode. |
| | D) | when a cloud of helium starts to collapse and breaks into constituent protons (hydrogen atoms). |
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22 | |
White dwarfs |
| | A) | are believed to be very small, perhaps about the size of the earth. |
| | B) | contain atoms that have collapsed in the center, yet retain the standard distances between nuclei and electrons. |
| | C) | are totally hypothetical stars, based on the best theories, but have never been observed directly. |
| | D) | are found only on the far edge of the universe. |
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23 | |
A star in the main sequence will maintain a constant size |
| | A) | as long as its helium supply holds out. |
| | B) | because its tendency to contract is opposed by the pressure of the hot interior. |
| | C) | until it is devoured by black holes. |
| | D) | provided that gravitational collapse does not overwhelm its photosphere. |
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24 | |
A black dwarf |
| | A) | is the final end of result of the life cycle of a star like our sun. |
| | B) | is a lump of matter that was once a star but has ceased to give off radiation. |
| | C) | is a stage after a white dwarf, but the universe is not thought to be old enough for any white dwarf to have become black dwarfs yet. |
| | D) | all of the above are true of black dwarfs. |
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25 | |
Supernovae |
| | A) | are an intermediate stage in the life of most stars. |
| | B) | create immense amounts of radiation that are outside of the visible spectrum, so none have ever been observed by naked eye observations. |
| | C) | are the result of exploding stars that initially are more than about eight times the sun's mass. |
| | D) | explosions are relatively slow, typically taking about three to four million years. |
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