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  3. Astronomers found a large body orbiting close to the star Upsilon Andromedae. Th

Astronomers found a large body orbiting close to the star Upsilon Andromedae. Th

游客2024-01-11  31
问题 Astronomers found a large body orbiting close to the star Upsilon Andromedae. The standard theory of planet formation holds that no planet that large could be formed so close to a star, leading to the suggestion that the body is a companion star. A subsequent discovery puts that suggestion in doubt: two other large bodies were found orbiting close to Upsilon Andromedae, and the standard theory of companion stars allows for at most one companion star.
选项 A、The smaller a planet orbiting a star is, and the farther away it is from the star, the less likely it is to be discovered.
B、If a planet’s orbit is disturbed, the planet can be drawn by gravity toward the star it is orbiting.
C、The largest of the bodies orbiting Upsilon Andromedae is the farthest away from the star, and the smallest is the nearest.
D、It is likely that there are many stars, in addition to Upsilon Andromedae and the Sun, that are orbited by more than one smaller body.
E、In most cases of companion stars, the smaller companion is much fainter than the larger star.
答案 B
解析 The passage outlines a conflict between two standard theories—one of planet formation, the other of companion stars — and observations of one large body, and later two others, orbiting close to a star. The question asks what would resolve this conflict without casting doubt on either one of the theories.
    Choice B is correct: if, as it asserts, it is possible for a planet to be formed relatively far from a star and later move closer to it, then the observed large bodies found close to Upsilon Andromedae can be planets without casting doubt on the standard theory of planet formation. This explanation also leaves the standard theory of companion stars intact.
    Choice A is incorrect because it describes difficulties with discovering a small planet far from a star, not anything pertaining to a large body near a star. Choice C is incorrect as well, since whatever the relative size and position of the three bodies may be, all three appear to be too close according to the standard theories. Choice D is incorrect because the pervasiveness of stars with multiple orbiting bodies has nothing to do with the status of the large bodies discussed in the passage. Choice E is similarly irrelevant and thus incorrect: information about the brightness of a star relative to its companion star does not help clarify the status of the large bodies discussed in the passage.
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