科學(xué)家揭開了“棉花糖”行星的秘密

科學(xué)家揭開了“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.

“超級(jí)泡芙”可能聽起來(lái)像你在雜貨店買到的甜食，但這些“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.

美國(guó)國(guó)家航空航天局(NASA)的科學(xué)家們?cè)诓粩嘣黾拥墓胀h(yuǎn)鏡數(shù)據(jù)的推動(dòng)下，正在研究新的數(shù)據(jù)，這些數(shù)據(jù)顯示，在一顆名為Kepler-51的類似太陽(yáng)的年輕恒星周圍，存在著3個(gè)超級(jí)噴流。

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.

這些膨脹的系外行星大約有木星那么大，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.

它們于2012年被發(fā)現(xiàn)，并于2014年確定了它們的密度。然而，直到本周來(lái)自哈勃的數(shù)據(jù)才使天文學(xué)家得以完善并獨(dú)立確認(rèn)這些行星的質(zhì)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.

天文學(xué)家將這些超級(jí)巨星分別命名為Kepler-51 b、Kepler-51 c和Kepler-51 d。正如你在下圖中看到的，它們的氫和/或氦大氣層膨脹得幾乎和木星一樣大。

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.

美國(guó)國(guó)家航空和宇宙航行局的研究人員還用哈勃望遠(yuǎn)鏡研究了這些新膨脹行星大氣的化學(xué)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.

他們?cè)詾槟苷业剿嫩欅E，但令他們吃驚的是，他們只發(fā)現(xiàn)了鹽晶體云和光化學(xué)煙霧。這種成分類似于土星最大的衛(wèi)星——土衛(wèi)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!"

“這完全出乎意料，”科羅拉多大學(xué)博爾德分校的杰西卡·利比-羅伯茨說(shuō)。“我們本打算觀察大的吸水特征，但它們就是不存在。我們被云遮住了!”

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.

研究小組將這些超級(jí)噴流與其他富含氣體的行星進(jìn)行了比較。他們能夠確定一顆行星的溫度越低，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結(jié)論，低密度是由于年輕的系統(tǒng)。

Their system is roughly 500 million years old, which pales in comparison to our 4.6-billion-year-old sun.

他們的系統(tǒng)大約有5億年的歷史，和我們46億年前的太陽(yáng)相比就相形見絀了。

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.

科學(xué)家們認(rèn)為，這些年輕的系外行星形成于它們的恒星的“雪線”之外，行星的軌道允許冰物質(zhì)的存在。然后，超級(jí)吹氣向內(nèi)遷移。

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.

美國(guó)宇航局的研究人員認(rèn)為，隨著時(shí)間的推移，低密度大氣將會(huì)蒸發(fā)。這將把一個(gè)像Kepler-51 b那樣的超級(jí)膨脹變成一個(gè)更小更熱的海王星。

"This system offers a unique laboratory for testing theories of early planet evolution," said Zach Berta-Thompson of the University of Colorado, Boulder.

“這個(gè)系統(tǒng)為測(cè)試早期行星演化理論提供了一個(gè)獨(dú)特的實(shí)驗(yàn)室，”博爾德科羅拉多大學(xué)的Zach Berta-Thompson說(shuō)。

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.

雖然這些“棉花糖”行星的許多細(xì)節(jié)仍然是一個(gè)謎，但美國(guó)宇航局正依靠即將發(fā)射的詹姆斯·韋伯太空望遠(yuǎn)鏡來(lái)進(jìn)一步了解它們的構(gòu)成。