GRE课程
Questions 1 and 3 are based on this passage
The recently announced discovery of the first known planet orbiting a pulsar (the ultradense, pulsating remnant off the supernova explosion of a star) turned out to be based on faulty data. Had this discovery been confirmed, theorists would have had difficulty accounting for the existence of such a planet. The supernova would certainly have destroyed any preexisting planets. This particular pulsar is relatively young, allowing little time for a new planet to have coalesced, and it rotates relatively slowly, implying that it has not interacted with any nearby star since the supernova. But newer evidence of a different pulsar with planets is more promising. This is a rapidly spurring “millisecond pulsar” thought to be a much older object that has pulled gaseous material from a stellar neighbor, causing its rotational speed to increase. Leftover, unconsumed gas around such a pulsar could, in theory, coalesce into planets. Or the pulsar’s radiation might have vaporized a companion star, providing new material for planetary formation.
Which of the following can be inferred regarding the pulsar discussed in the first paragraph?
Theorists initially doubted its existence
If its existence had been confirmed, astronomers would and have turned their attention to the pulsar discussed in the second paragraph.
If the supernovas explosions that created it had been more powerful, the resulting radiation would have preceded the subsequent formation of a planet.
If it had interacted with a nearby star since the supernova explosion, it would rotate faster than it does.
Astronomers’ interest in it ultimately led to a new theory of planetary formation.
Select one answer choice.
