對于我們的宇宙學(xué)模型來說，最早的恒星形成得太快了

新的證據(jù)表明，對于我們的宇宙學(xué)模型來說，最早的恒星形成得太快了

When we think about the formation of the entire freaking Universe, one of the biggest questions concerns the birth of the very first stars. It's thought that stars began appearing in the first 100 million years after the Big Bang, and we've seen some really old stars; but the processes that created them from the primordial Universe soup are a big mystery.

當(dāng)我們思考整個宇宙的形成時，其中一個最大的問題是關(guān)于最早的恒星的誕生。人們認(rèn)為，恒星是在大爆炸后的1億年開始出現(xiàn)的，我們看到過一些非常古老的恒星;但是從原始宇宙湯中產(chǎn)生它們的過程是一個很大的謎。

But a gas cloud in the distant Universe has just given us a big clue. It's so far away, light from this cloud has taken nearly 13 billion years to arrive, meaning we're seeing the cloud as it was when the Universe was roughly 850 million years old - a mere blip of its current lifespan.

但是遙遠(yuǎn)宇宙中的氣體云給了我們一個重要的線索。它是如此的遙遠(yuǎn)，來自這片云的光花了近130億年才到達(dá)，這意味著我們看到的這片云和宇宙大約8.5億年的時候是一樣的——只是它目前壽命的一個小點。

That cloud looks rather similar to younger gas clouds filled with elements that were forged in stars and spewed out into space in a series of explosions as those stars died. This indicates there would have been stars around that had already lived and died by 13 billion years ago.

這片云看起來很像年輕的氣體云，充滿了在恒星中形成的元素，這些元素在恒星死亡時通過一系列爆炸噴射到太空中。這表明在130億年前就已經(jīng)存在和死亡的恒星。

Not just one generation, either. Based on the chemical abundances in this ancient gas cloud, at least two generations of stars had to form, live, and die to produce the chemical signature we're seeing.

也不只是一代人。根據(jù)這個古老氣體云中的化學(xué)元素豐度，至少有兩代恒星必須形成、生存和死亡，才能產(chǎn)生我們所看到的化學(xué)特征。

It's a real dilly of a pickle for our models of star formation, and it was discovered entirely by accident.

對于我們的恒星形成模型來說，這是一個真正的難題，它完全是偶然發(fā)現(xiàn)的。

Astronomer Eduardo Bañados of the Max Planck Institute for Astronomy and colleagues were looking at distant quasars - galaxies with extremely bright active nuclei, or cores. When the team noticed something odd about the light from a quasar called P183+05, around 13 billion light-years away, they decided to take a closer look.

馬克斯·普朗克天文研究所的天文學(xué)家愛德華多·巴納多斯和他的同事們一直在觀察遙遠(yuǎn)的類星體——擁有極其明亮的活動核或核心的星系。當(dāng)研究小組注意到一個名為P183+05的類星體發(fā)出的光有些奇怪時，他們決定近距離觀察。

It didn't take long before they realised that the odd signatures in the light were from a cloud of gas and dust near the quasar, through which some of the quasar's light was being filtered, dampening some of the wavelengths.

沒過多久，他們就意識到這些奇怪的信號來自于類星體附近的一團氣體和塵埃，通過這些氣體和塵埃，一些類星體的光被過濾了，減弱了一些波長。

(Max Planck Institute for Astronomy)

Because different wavelengths of light are blocked by different elements, this also provided clues as to the composition of the cloud.

因為不同的光波被不同的元素阻擋，這也為云的組成提供了線索。

After we were convinced that we were looking at such pristine gas only 850 million years after the Big Bang, said astronomer Michael Rauch of the Carnegie Institution of Science, "we started wondering whether this system could still retain chemical signatures produced by the very first generation of stars."

卡內(nèi)基科學(xué)研究所的天文學(xué)家邁克爾·勞赫說:“我們確信，我們是在大爆炸后8.5億年才觀測到這樣的原始?xì)怏w。我們開始懷疑，這個系統(tǒng)是否還能保留第一代恒星產(chǎn)生的化學(xué)信號。”

In the very early Universe, there wasn't a lot of variety. Just after the Big Bang, the Universe was mostly filled with hydrogen and helium. It wasn't until the first stars came along that more elements started to proliferate.

在非常早期的宇宙中，沒有太多的多樣性。大爆炸后不久，宇宙主要由氫和氦組成。直到第一批恒星出現(xiàn)，更多的元素才開始增殖。

In their cores, stars fused hydrogen into helium, then helium into carbon, and so forth, with the more massive stars able to fuse nuclei all the way up to iron. When such stars reach the end of their lives and go supernova, the extreme conditions of these explosions can, in turn, create heavier elements.

在它們的核心中，恒星將氫聚變成氦，然后氦聚變成碳，以此類推，質(zhì)量更大的恒星能夠?qū)⒃雍艘恢本圩兊借F。當(dāng)這些恒星到達(dá)生命的盡頭并變成超新星時，這些爆炸的極端條件反過來會產(chǎn)生更重的元素。

These are taken up into new generations of stars - thus, the more metals there are in a star, the younger its generation is likely to be. And those signatures can also be used to tell the age of the gas between the stars - the interstellar medium.

這些元素被吸收到新一代的恒星中——因此，一顆恒星中的金屬元素越多，它的新一代可能就越年輕。這些特征也可以用來判斷恒星間氣體的年齡——星際介質(zhì)。

Which brings us back to that super-old gas cloud. Something of a holy grail in cosmology is finding the chemical fingerprints of the very first generation of stars, known as Population III. The team thought that their gas cloud might have them.

這讓我們回到了那個超級古老的氣體云。找到第一代恒星的化學(xué)指紋是宇宙學(xué)中的圣杯，也就是我們所知的第三種群。研究小組認(rèn)為，他們的氣體云可能會把它們帶走。

So, they analysed the metallicity and relative chemical abundances in the cloud, based on spectra separated out from the light of the quasar.

因此，他們根據(jù)從類星體中分離出的光譜分析了云團中的金屬豐度和相對化學(xué)豐度。

As expected, the cloud had low metallicity, consistent with its age. But the relative chemical abundances had no evidence of being enriched by Population III stars. Rather, they were startlingly similar to those of much younger gas clouds enriched by Type Ia supernovae.

不出所料，這片云的金屬豐度很低，與它的年齡相符。但相對的化學(xué)元素豐度并沒有被星族III豐富的證據(jù)。相反，它們與Ia型超新星豐富的年輕氣體云驚人地相似。

What that means is that another generation of stars separates the cloud from Population III stars - and, since Type Ia supernovae generally take around a billion years… well. We have a discrepancy.

這意味著新一代的恒星會將星云與第三類恒星分開——而且，由于Ia型超新星一般需要大約10億年的時間……我們有分歧。

That puts a curious constraint on the life cycles of early stars, which is going to be an interesting puzzle to solve. But there's other evidence to suggest that the early Universe is a pretty precocious place - such as a whole bunch of supermassive black holes that we don't think could have formed so quickly.

這給早期恒星的生命周期帶來了一個奇怪的限制，這將是一個需要解決的有趣難題。但也有其他證據(jù)表明，早期宇宙是一個相當(dāng)早熟的地方——比如一大堆我們認(rèn)為不可能這么快就形成的超大質(zhì)量黑洞。

If this finding checks out, maybe it's time to give the cosmological models a do-over.

如果這一發(fā)現(xiàn)得到證實，也許是時候?qū)τ钪鎸W(xué)模型進(jìn)行重新研究了。

Meanwhile, the team is continuing to search for clues.

與此同時，調(diào)查小組仍在繼續(xù)尋找線索。

It is exciting that we can measure metallicity and chemical abundances so early in the history of the Universe, but if we want to identify the signatures of the first stars we need to probe even earlier in cosmic history, Bañados said.

Banados說:“我們能夠在宇宙早期歷史中測量金屬豐度和化學(xué)豐度是令人興奮的，但是如果我們想要確定第一批恒星的特征，我們需要在宇宙歷史中更早的時候進(jìn)行探測。”

I am optimistic that we will find even more distant gas clouds, which could help us understand how the first stars were born.

“我很樂觀地認(rèn)為，我們將發(fā)現(xiàn)更遠(yuǎn)的氣體云，這將有助于我們了解第一批恒星是如何誕生的。”

The research is due to be published in The Astrophysical Journal, and is available on arXiv.

這項研究將發(fā)表在《天體物理學(xué)雜志》(Astrophysical Journal)上，可以在arXiv上找到。