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  3. Astronomers have had difficulty accounting for certain planets discovered ou

Astronomers have had difficulty accounting for certain planets discovered ou

游客2024-01-10  22
问题     Astronomers have had difficulty accounting for certain planets discovered outside our solar system. They are called hot Jupiters because each is similar in mass to Jupiter, the largest solar-system planet, but orbits its parent star at a fraction of the distance at which Earth, let alone Jupiter, orbits the Sun. In the standard, solar-system-based theory of planetary formation, such as a massive planet could not form so close to a star. So most attempts to explain a hot Jupiter’s existence envision it forming farther away, then migrating inward. According to one hypothesis, the planet’s gravitational field tugs on the protoplanetary disk of dust and gas from which it formed. The disk exerts its own gravitational tug, and this interplay of forces robs the planet of momentum in its orbital path, forcing it to spiral in toward the star. According to another hypothesis, the planet’s gravitational field is so strong that it creates a groove in the disk, partitioning it into inner and outer regions; the resulting gravitational interactions between the planet and these regions cause the planet to lose orbital momentum and spiral inward. Another question remains: what prevents the planet from continuing its spiral until it collides with the star? [br] It can be inferred from the passage that the “attempts” share which of the following goals?
选项 A、to explain how a Jupiter-sized planet could form so close to its parent star.
B、to explain what prevents a hot Jupiter from colliding with its parent star.
C、to determine whether a hot Jupiter is formed from a protoplanetary disk of dust and gas.
D、to determine whether a hot Jupiter’s gravitational field is strong enough to create a groove in its protoplantary disk
E、to account for hot Jupiters in a way that is not inconsistent with the standard theory of planetary formation.
答案 E
解析 定位到第四句，这些尝试给出的解释是热木星形成于远处，之后迁移到近的地方。而之前的标准理论认为热木星这种质量的星体不会在那么靠近恒星的地方形成，因此这些“尝试”是按照符合标准理论说法的方式去解释热木星的，故选项E正确。A项容易错选，注意第四句的forming father away，then migrating inward，因此这些“尝试”认为是热木星形成于远的地方。B项根据文章最后一句，这依然是个悬而未决的问题。C项之后的两个假说都说热木星形成于这种星盘。D项是假说二的内容，而且文章本身没有确定引力场是否足够强大。
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