矮行星2007 OR10上发现冰水
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Astronomers1 at the California Institute of Technology (Caltech) have discovered that the dwarf2 planet 2007 OR10 -- nicknamed Snow White -- is an icy world, with about half its surface covered in water ice that once flowed from ancient, slush-spewing volcanoes. The new findings also suggest that the red-tinged dwarf planet may be covered in a thin layer of methane3(甲烷) , the remnants of an atmosphere that's slowly being lost into space. "You get to see this nice picture of what once was an active little world with water volcanoes and an atmosphere, and it's now just frozen, dead, with an atmosphere that's slowly slipping away," says Mike Brown, the Richard and Barbara Rosenberg Professor and professor of planetary astronomy, who is the lead author on a paper to be published in the Astrophysical Journal Letters describing the findings. The paper is now in press.

Snow White -- which was discovered in 2007 as part of the PhD thesis of Brown's former graduate student Meg Schwamb -- orbits the sun at the edge of the solar system and is about half the size of Pluto4, making it the fifth largest dwarf planet. At the time, Brown had guessed incorrectly that it was an icy body that had broken off from another dwarf planet named Haumea; he nicknamed it Snow White for its presumed white color.

Soon, however, follow-up observations revealed that Snow White is actually one of the reddest objects in the solar system. A few other dwarf planets at the edge of the solar system are also red. These distant dwarf planets are themselves part of a larger group of icy bodies called Kuiper Belt Objects (KBOs). As far as the researchers could tell, Snow White, though relatively5 large, was unremarkable -- just one out of more than 400 potential dwarf planets that are among hundreds of thousands of KBOs.

"With all of the dwarf planets that are this big, there's something interesting about them -- they always tell us something," Brown says. "This one frustrated6 us for years because we didn't know what it was telling us." At that time, the Near Infrared7 Camera (NIRC) at the Keck Observatory8 -- which Caltech professor of physics Tom Soifer and chief instrument scientist Keith Matthews helped design in the 1990s -- was the best instrument astronomers had to study KBOs, according to Brown. But NIRC had just been retired9, so no one could observe 2007 OR10 in detail. "It kind of languished10(失去活力) ," he says.

Meanwhile, Adam Burgasser, a former graduate student of Brown's and now a professor at UC San Diego, was helping11 to design a new instrument called the Folded-port Infrared Echellette (FIRE). Last fall, Brown, Burgasser, and postdoctoral scholar Wesley Fraser used this instrument with the 6.5-meter Magellan Baade Telescope in Chile to take a closer look at 2007 OR10.

As expected, Snow White was red. But to their surprise, the spectrum12 revealed that the surface was covered in water ice. "That was a big shock," Brown says. "Water ice is not red." Although ice is common in the outer solar system, it's almost always white.


1 astronomers 569155f16962e086bd7de77deceefcbd     
n.天文学者,天文学家( astronomer的名词复数 )
  • Astronomers can accurately foretell the date,time,and length of future eclipses. 天文学家能精确地预告未来日食月食的日期、时刻和时长。 来自《简明英汉词典》
  • Astronomers used to ask why only Saturn has rings. 天文学家们过去一直感到奇怪,为什么只有土星有光环。 来自《简明英汉词典》
2 dwarf EkjzH     
  • The dwarf's long arms were not proportional to his height.那侏儒的长臂与他的身高不成比例。
  • The dwarf shrugged his shoulders and shook his head. 矮子耸耸肩膀,摇摇头。
3 methane t1Eyx     
  • The blast was caused by pockets of methane gas that ignited.爆炸是由数袋甲烷气体着火引起的。
  • Methane may have extraterrestrial significance.甲烷具有星际意义。
4 Pluto wu0yF     
  • Pluto is the furthest planet from the sun.冥王星是离太阳最远的行星。
  • Pluto has an elliptic orbit.冥王星的轨道是椭圆形的。
5 relatively bkqzS3     
  • The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
  • The operation was relatively painless.手术相对来说不痛。
6 frustrated ksWz5t     
adj.挫败的,失意的,泄气的v.使不成功( frustrate的过去式和过去分词 );挫败;使受挫折;令人沮丧
  • It's very easy to get frustrated in this job. 这个工作很容易令人懊恼。
  • The bad weather frustrated all our hopes of going out. 恶劣的天气破坏了我们出行的愿望。 来自《简明英汉词典》
7 infrared dx0yp     
  • Infrared is widely used in industry and medical science.红外线广泛应用于工业和医学科学。
  • Infrared radiation has wavelengths longer than those of visible light.红外辐射的波长比可见光的波长长。
8 observatory hRgzP     
  • Guy's house was close to the observatory.盖伊的房子离天文台很近。
  • Officials from Greenwich Observatory have the clock checked twice a day.格林威治天文台的职员们每天对大钟检查两次。
9 retired Njhzyv     
  • The old man retired to the country for rest.这位老人下乡休息去了。
  • Many retired people take up gardening as a hobby.许多退休的人都以从事园艺为嗜好。
10 languished 661830ab5cc19eeaa1acede1c2c0a309     
长期受苦( languish的过去式和过去分词 ); 受折磨; 变得(越来越)衰弱; 因渴望而变得憔悴或闷闷不乐
  • Our project languished during the holidays. 我们的计划在假期间推动得松懈了。
  • He languished after his dog died. 他狗死之后,人憔悴了。
11 helping 2rGzDc     
  • The poor children regularly pony up for a second helping of my hamburger. 那些可怜的孩子们总是要求我把我的汉堡包再给他们一份。
  • By doing this, they may at times be helping to restore competition. 这样一来, 他在某些时候,有助于竞争的加强。
12 spectrum Trhy6     
  • This is a kind of atomic spectrum.这是一种原子光谱。
  • We have known much of the constitution of the solar spectrum.关于太阳光谱的构成,我们已了解不少。
TAG标签: water planet ice