在我們的太陽系中有一個(gè)“大分水嶺”，我們可能最終知道它是如何形成的

在我們的太陽系中有一個(gè)“大分水嶺”，我們可能最終知道它是如何形成的

Shortly after the Solar System formed, astronomers think it went through what's known as the Great Divide – a splitting up of the planets into two distinct groups. We weren't around to experience this cosmic schism, but a new study has put forward an intriguing hypothesis on how it would have occurred.

太陽系形成后不久，天文學(xué)家認(rèn)為它經(jīng)歷了所謂的“大分水嶺”——行星分裂成兩個(gè)不同的組。我們并沒有經(jīng)歷這種宇宙分裂，但一項(xiàng)新的研究提出了一個(gè)有趣的假設(shè)，它是如何發(fā)生的。

Put simply, the Great Divide left our Solar System with the smaller terrestrial planets closest to the Sun (including Earth and Mars), and the larger gas giant - or 'Jovian' - planets farther out (including Jupiter and Saturn).

簡而言之，大分水嶺讓我們的太陽系只剩下了離太陽最近的較小的類地行星(包括地球和火星)和離太陽更遠(yuǎn)的較大的氣態(tài)巨行星(或稱“木星”)(包括木星和土星)。

Not only do these two groups of planets differ in size, they're different in their make-up: terrestrial planets are largely composed of rock and lacking in organic carbon compounds, whereas the Jovian planets are largely made up of gas, and rich in organics.

這兩類行星不僅大小不同，它們的構(gòu)成也不同:類地行星主要由巖石構(gòu)成，缺乏有機(jī)碳化合物;而木星行星主要由氣體構(gòu)成，富含有機(jī)物。

The question is: how do you create this compositional dichotomy? says planetary scientist Ramon Brasser from the Tokyo Institute of Technology in Japan.

日本東京理工學(xué)院的行星科學(xué)家Ramon Brasser說:“問題是:你如何創(chuàng)造這種成分二分法?”

How do you ensure that material from the inner and outer Solar System didn't mix from very early on in its history?

“你如何確保太陽系內(nèi)外的物質(zhì)在它的早期歷史中沒有混合?”

Up until now, we've been pinning the blame on the gravitational effects of Jupiter. According to this idea, the pull of the massive planet was enough to create a kind of invisible barrier between the inner and outer planets.

到目前為止，我們一直將其歸咎于木星的引力效應(yīng)。根據(jù)這個(gè)想法，大質(zhì)量行星的引力足以在內(nèi)外行星之間形成一種無形的屏障。

But Brasser and colleagues think this may not be the case. Their calculations point to a ring-like structure forming around the early Sun, creating a disk that acted as a physical barrier between two types of planet-forming materials.

但是Brasser和他的同事們認(rèn)為事實(shí)并非如此。他們的計(jì)算指出，在早期的太陽周圍形成了一個(gè)環(huán)狀結(jié)構(gòu)，形成了一個(gè)圓盤，充當(dāng)了兩種行星形成材料之間的物理屏障。

The most likely explanation for that compositional difference is that it emerged from an intrinsic structure of this disk of gas and dust, says geological scientist Stephen Mojzsis, from the University of Colorado Boulder.

來自科羅拉多大學(xué)博爾德分校的地質(zhì)學(xué)家Stephen Mojzsis說:“對于這種成分上的差異，最有可能的解釋是它來自于這個(gè)由氣體和塵埃組成的圓盤的內(nèi)在結(jié)構(gòu)。”

Computer simulations run by the researchers showed that Jupiter wouldn't have been big enough in the early Solar System to block the flow of rocky material towards the Sun. If Jupiter didn't cause the schism, the team had to look for an alternative explanation.

研究人員進(jìn)行的計(jì)算機(jī)模擬顯示，在早期的太陽系中，木星的體積還不足以阻擋巖石物質(zhì)向太陽的流動。如果不是木星造成的分裂，研究小組不得不尋找另一種解釋。

They found it in data from the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, which showed disks of gas and dust around fledgling stars. If such a ring had originally formed around our own star, it might have separated gas and dust into separate pockets of high and low pressure.

他們在智利的阿塔卡馬大型毫米/亞毫米陣列(ALMA)的數(shù)據(jù)中發(fā)現(xiàn)了這一現(xiàn)象。如果這樣一個(gè)環(huán)最初是在我們自己的恒星周圍形成的，它可能會把氣體和塵埃分離到不同的高氣壓和低壓區(qū)。

The researchers describe it as a "pressure bump", capable of sorting material into two distinct buckets in the early days of the Solar System. In fact, there may have been several rings responsible for creating the divide in planet types.

研究人員將其描述為一個(gè)“壓力沖擊”，能夠在太陽系早期將物質(zhì)分成兩部分。事實(shí)上，可能有幾個(gè)光環(huán)造成了行星類型的差異。

How materials were sorted in the early Solar System is also important knowledge for understanding the emergence of life on Earth.

在太陽系早期，物質(zhì)是如何被分類的，這對于理解地球上生命的出現(xiàn)也很重要。

Unlike the other terrestrial planets, ours bucks the trend by containing organic materials, suggesting those dividing disks wouldn't necessarily have been completely uncrossable – and fugitive carbon-rich materials may have scattered across the divide to trigger life on Earth.

與其他類地行星不同的是，我們的類地行星通過包含有機(jī)物質(zhì)來逆潮流而動，這表明那些分開的圓盤并不一定是完全不可交叉的——易流失的富含碳的物質(zhì)可能散布在分水嶺上，觸發(fā)了地球上的生命。

This is yet another example of how studying growing star systems elsewhere in the cosmos can tell us more about how our own Solar System came into being, and about the first hints of life in our solar neighbourhood, too.

這是另一個(gè)研究宇宙中其他地方不斷成長的恒星系統(tǒng)的例子，它可以告訴我們更多關(guān)于我們自己的太陽系是如何形成的，以及關(guān)于我們的太陽鄰居最初的生命跡象。

The research is published in Nature Astronomy.

這項(xiàng)研究發(fā)表在《自然天文學(xué)》雜志上。