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  3. Sunspots act like planet-sized hurricanes that suck in as much material as they spew out, temporarily overriding the laws of mag

Sunspots act like planet-sized hurricanes that suck in as much material as they spew out, temporarily overriding the laws of mag

admin2015-09-26  25
问题     Sunspots act like planet-sized hurricanes that suck in as much material as they spew out, temporarily overriding the laws of magnetic fields, scientists said on Tuesday.
    A team of researchers from NASA and Stanford University said by peering into the Sun for the first time, they discovered how the magnetic fields, which make up the cool dark sunspots on the surface, clump together instead of dispersing. Scientists had previously observed gases pouring out of the sunspots, and thought this was the product of the various magnetic fields repelling each other, in the same way magnets repel each other when brought together. But the researchers said the out-flowing matter is just a surface feature that occurs while the sunspot sucks in new material to hold itself together.
    "If you look a bit deeper, you find material rushing inward, like a planet-sized whirlpool or hurricane. This inflow pulls the magnetic fields(back)together," said Junwei Zhao, one of the Stanford researchers. The pressure in this sunspot hurricane is about 10 times higher than a tropical hurricane on Earth, scientists said. "Without this flow, a sunspot would not last a day. With it, it lasts for weeks. In the end, the sunspot does get torn apart—but we still don’t know how yet," Stanford colleague Philip Scherrer, said at a news conference.
    To get this deeper knowledge the team used sound wave technology, which they likened to the ultrasound doctors use to capture images of unborn babies. The research showed the magnetic field below a sunspot would cut off the spot’s supply of energy from the Sun’s hot core, turning it into a plug. Any matter above the plug would then cool and become denser, until gravity dragged it and any surrounding gases into the center of the spot at 3,000 miles per hour. "As long as the magnetic field remains strong, the coding effect will maintain an inflow that makes the structure stable... thereby setting up a self-perpetuating cycle, " the team said in its report.
    British scientist Douglas Gough from Cambridge University, described the group’s findings as the solution to a 400-year-old riddle. Understanding the sunspot component would help scientists gain a global knowledge of the Sun, he said. "Take a TV set. It is not simply the sum of its components. And trying to understand the whole requires a greater global knowledge, but you can’t build a TV set unless you know how the components work. It’s the same with the Sun and its components," Gough said.
    The findings are the latest in a long line of sunspot research, which stems back to the early 17th century, when Italian astronomer Galileo Galilei used sunspots to calculate the speed of the Sun’s rotation. His hand-drawn renditions of sunspot locations contrasted sharply with the computer-generated multicolored models of sunsoots on display at NASA’s Washington headquarters. "Imagine yourself flying over a lake, you can see the surface but you don’t know how deep it is, how the temperature varies with depth. It was the same with sunspots until now," NASA’s George Withbroe said.
The passage is mainly concerned with______.
选项 A、the components of sunspots
B、sunspots acting like planet-sized hurricanes
C、a better understand of the sun
D、sunspots and the hurricanes
答案B
解析 主旨题。本文在第一段就明确指出了中心议题，即美国科学家认为太阳黑子就像行星飓风一样活动，通过后文还可知这是对太阳黑子研究的最新发现，所以选[B]。[A]“太阳黑子的成分”，文章并未对此展开说明和论证；[C]“对太阳的更好了解”，与主题“太阳黑子”不符；[D]“太阳黑子与飓风”，文章只是在开头将太阳黑子比作planet—sized hurricanes，其余部分并未具体讲述飓风以及两者之间的关系，故排除。
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