天文学家首次在另一个星系中发现了分子氧

天文学家首次在另一个星系中发现了分子氧

In a wild galaxy over half a billion light-years away, astronomers have detected molecular oxygen. It's only the third such detection ever outside the Solar System - and the first outside the Milky Way.

在5亿光年之外的一个野生星系中，天文学家已经探测到了分子氧。这只是太阳系之外的第三次探测，也是银河系之外的第一次。

Oxygen is the third most abundant element in the Universe, behind hydrogen (naturally) and helium. So its chemistry and abundance in interstellar clouds are important for understanding the role of molecular gas in galaxies.

氧是宇宙中第三丰富的元素，仅次于氢(自然)和氦。因此，它的化学性质和在星际云中的丰度对于理解星系中分子气体的作用非常重要。

Astronomers have searched for oxygen again and again, using millimetre astronomy, which detects the radio wavelengths emitted by molecules; and spectroscopy, which analyses the spectrum to look for wavelengths absorbed or emitted by specific molecules.

天文学家一次又一次地寻找氧气，他们尝试了毫米天文学(探测分子发射的无线电波长)和光谱学(分析光谱，寻找特定分子吸收或发射的波长)这两种工具。

But these searches have turned up a puzzling lack of oxygen molecules. Which means "a comprehensive picture of oxygen chemistry in different interstellar environments is still missing," wrote a team of astronomers led by Junzhi Wang of the Chinese Academy of Sciences in a new paper.

但是这些研究发现了一个令人费解的缺乏氧分子的现象，中国科学院领导的一个天文学家团队在一篇新论文中写道，这意味着“不同星际环境中氧化物的全面图像仍然缺失”。

One place molecular oxygen has been detected is the Orion nebula; it's been hypothesised that out in space, oxygen is bound up with hydrogen in the form of water ice that is clinging to dust grains.

已经探测到分子氧的一个地方是猎户座星云，据推测，那里的氧与氢结合在一起，以冰的形式附着在尘埃颗粒上。

But the Orion nebula is a stellar nursery, and it's possible that the intense radiation from very hot young stars shocks the water ice into sublimation and splits the molecules, releasing the oxygen.

但猎户座星云是一个恒星托儿所，因此年轻恒星很有可能发出的强烈辐射冲击这些冰，使其升华并分解，释放氧气。

Which brings us to a galaxy called Markarian 231.

这些使研究人员想到了名为马卡里安231的星系。

Markarian 231 is special. It's 561 million light-years away, and powered by a quasar. That's an extremely luminous galactic nucleus with an active supermassive black hole in the centre. They're the brightest objects in the Universe, and Markarian 231 contains the closest quasar to Earth.

马卡里安231很特别。它距离地球5.61亿光年，由类星体提供能量。类星体一个非常明亮的星系核心，中心有一个活跃的超大质量黑洞。它们是宇宙中最明亮的天体，而马尔卡里安231包含了离地球最近的类星体。

In fact, astronomers think Markarian 231 might have two active supermassive black holes in its centre, whirling around each other at a furious rate.

事实上，天文学家认为马卡里安231可能在其中心有两个活动的超大质量黑洞，它们以极快的速度相互旋转。

An active galactic nucleus drives molecular outflows, producing continuous shocks of the kind that might release oxygen from water in molecular clouds.

活跃的星系核驱动分子外流，产生连续的冲击，这种冲击可能会从分子云中的水释放氧气。

Using the IRAM 30-metre radio telescope in Spain, they took observations of the galaxy for four days across a number of wavelengths. In those data, they found the spectral signature of oxygen, in line with the shock hypothesis.

他们利用西班牙的IRAM 30米射电望远镜，在多个波长上对银河系进行了为期4天的观测。在这些数据中，他们发现了氧气的光谱特征，与冲击假说一致。

"With deep observations toward Markarian 231 using the IRAM 30 meter telescope and NOEMA, we detected [molecular oxygen] emission in [an] external galaxy for the first time," the researchers wrote in their paper.

研究人员在论文中写道：“通过使用IRAM 30米望远镜和NOEMA对马卡里安231进行深入观测，我们首次探测到外部星系中的[分子氧]。”。

"The detected O2 emission is located in regions about 10 kpc (32,615 light-years) away from the center of Markarian 231 and may be caused by the interaction between the active galactic nucleus-driven molecular outflow and the outer disc molecular clouds."

“探测到的分子氧位于距离马卡里安231中心约32,615光年的区域，可能是由活跃的星系核驱动的分子流出物和外围盘状分子云之间的相互作用产生的。”

The research has been published in The Astrophysical Journal.

这项研究已发表在《天体物理学杂志》上。