科学家揭开了“棉花糖”行星的秘密
"Super-puffs" may sound like a sweet treat you'd find at the grocery store, but these "cotton candy" exoplanets are much more interesting.
“超级泡芙”可能听起来像你在杂货店买到的甜食，但这些“棉花糖”系外行星要有趣得多。
Scientists at NASA, fueled by ever-increasing data from the Hubble Space Telescope, are studying new data that shows the existence of three super-puffs orbiting a young sun-like star called Kepler-51.
美国国家航空航天局(NASA)的科学家们在不断增加的哈勃太空望远镜数据的推动下，正在研究新的数据，这些数据显示，在一颗名为Kepler-51的类似太阳的年轻恒星周围，存在着3个超级喷流。
This illustration depicts the sun-like star Kepler 51 and three giant planets that Hubble discovered in 2012–2014. (Photo: NASA, ESA, and L. Hustak, J. Olmsted, D. Player and F. Summers (STScI))
These puffy exoplanets are roughly the size of Jupiter and have a similar density to cotton candy, thus the name.
这些膨胀的系外行星大约有木星那么大，密度和棉花糖差不多，因此得名。
They were discovered in 2012 and their densities were determined in 2014. However, it wasn't until this week that data from Hubble allowed astronomers to refine and independently confirm the mass and size estimates of these worlds.
它们于2012年被发现，并于2014年确定了它们的密度。然而，直到本周来自哈勃的数据才使天文学家得以完善并独立确认这些行星的质量和大小。
The super-puffs were labeled by astronomers as Kepler-51 b, Kepler-51 c and Kepler-51 d. As you can see in the photo below, their hydrogen and/or helium atmospheres are so bloated they're nearly the size of Jupiter.
天文学家将这些超级巨星分别命名为Kepler-51 b、Kepler-51 c和Kepler-51 d。正如你在下图中看到的，它们的氢和/或氦大气层膨胀得几乎和木星一样大。
This illustration depicts the three giant planets orbiting the sun-like star Kepler 51 as compared to some of the planets in our solar system. (Photo: NASA, ESA, and L. Hustak and J. Olmsted (STScI))
Researchers at NASA also used Hubble to examine the chemical components of the atmospheres of these new puff planets.
美国国家航空和宇宙航行局的研究人员还用哈勃望远镜研究了这些新膨胀行星大气的化学成分。
They expected to find traces of water, but to their surprise, they only found clouds of salt crystals and photochemical hazes. This composition is similar to Saturn's largest moon, Titan.
他们原以为能找到水的踪迹，但令他们吃惊的是，他们只发现了盐晶体云和光化学烟雾。这种成分类似于土星最大的卫星——土卫六。
"This was completely unexpected," said Jessica Libby-Roberts of the University of Colorado, Boulder. "We had planned on observing large water absorption features, but they just weren't there. We were clouded out!"
“这完全出乎意料，”科罗拉多大学博尔德分校的杰西卡·利比-罗伯茨说。“我们本打算观察大的吸水特征，但它们就是不存在。我们被云遮住了!”
The team of researchers compared the super-puffs to other gas-rich planets. They were able to determine the cooler a planet is, the cloudier it becomes.
研究小组将这些超级喷流与其他富含气体的行星进行了比较。他们能够确定一颗行星的温度越低，云量就越高。
Another part of the study concluded the lower densities are due to the young age of the system.
研究的另一部分得出结论，低密度是由于年轻的系统。
Their system is roughly 500 million years old, which pales in comparison to our 4.6-billion-year-old sun.
他们的系统大约有5亿年的历史，和我们46亿年前的太阳相比就相形见绌了。
Scientists believe these young exoplanets formed outside their star's "snow line," where a planet's orbit allow the existence of icy materials. Then, the super-puffs migrated inward.
科学家们认为，这些年轻的系外行星形成于它们的恒星的“雪线”之外，行星的轨道允许冰物质的存在。然后，超级吹气向内迁移。
Over time, NASA researchers believe the low-density atmospheres will evaporate. That would turn a super-puff like Kepler-51 b into a smaller and hotter version of Neptune.
美国宇航局的研究人员认为，随着时间的推移，低密度大气将会蒸发。这将把一个像Kepler-51 b那样的超级膨胀变成一个更小更热的海王星。
"This system offers a unique laboratory for testing theories of early planet evolution," said Zach Berta-Thompson of the University of Colorado, Boulder.
“这个系统为测试早期行星演化理论提供了一个独特的实验室，”博尔德科罗拉多大学的Zach Berta-Thompson说。
While many details of these "cotton candy" planets still remain a mystery, NASA is relying on the soon-to-be launched James Webb Space Telescope to learn even more about what they're made of.
虽然这些“棉花糖”行星的许多细节仍然是一个谜，但美国宇航局正依靠即将发射的詹姆斯·韦伯太空望远镜来进一步了解它们的构成。
