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Question
We find most stars still on the main sequence because this stage takes ________.Answer
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Related questions
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A galaxy with a blueshift is moving ________ Earth.
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When mass is accreted into a black hole, what fraction of the total mass-energy can be radiated away?
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Why is the energy source for active nuclei like Seyferts thought to be compact?
A) The sources appear to be single stars in photos.
B) Their energy appears to be non-stellar synchrotron radiation.
C) The light can vary over short time intervals.
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In active galaxies, their central engines may be temporarily fed by
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Describe the cycle of life and death we observe in the spiral arms.
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Compare the way an optical and radio astronomer would map the Galaxy.
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Why aren't there young stars in the halo?
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What advantage do radio astronomers have over optical ones in mapping the entire Milky Way?
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How did Herschel try to map our Galaxy 200 years ago, and why did he fail?
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The ________ is the spherical outer portion of the Galaxy, including the orbits of the globular clusters and most dark matter.
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Virtually the entire disk of the Galaxy has been mapped using the ________ wavelength.