离我们最近的恒星也有一颗地球大小的行星环绕着它

离我们最近的恒星也有一颗地球大小的行星环绕着它

Researchers have confirmed that our sun's nearest celestial neighbor — Proxima Centauri — has a planet in tow. And from here, it looks a lot like Earth.

研究人员已经证实，我们的太阳最近的天体邻居——比邻星拥有一颗行星。从这方面看，它很像地球。

The planet, according to research published this week in the journal Astronomy & Astrophysics, boasts a mass of 1.17 Earth masses and orbits its stars in a brisk 11.2 days. It's also in the so-called "Goldilocks zone" — meaning it holds to an orbit that’s neither too hot nor too cold for the possibility of liquid water.

根据本周发表在《天文学与天体物理学》杂志上的一项研究，这颗行星的质量为地球的1.17倍，围绕恒星公转的时间为11.2天。它也位于所谓的“适居带”——这意味着它的轨道既不太热也不太冷，不可能存在液态水。

And liquid water, of course, is something of a holy grail in the search for life beyond our planet. Not only that, but at 4.2 light- years away, it's relatively close. That proximity is why the existence of the planet, Proxima b, was already suspected back in 2013, according to The Independent.

当然，液态水是寻找外星生命的圣杯。不仅如此，在4.2光年之外，它也相当接近。据《独立报》报道，这就是为什么早在2013年，人们就怀疑比邻星的存在。

This artist's impression shows a view of the surface of the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to our solar system. (Photo: ESO/M. Kornmesser)

Its confirmation came courtesy of ESPRESSO, a new-generation spectrograph that’s mounted on the aptly named Very Large Telescope in Chile. Short for Echelle Spectrograph for Rocky Exoplanet and Stable Spectroscopic Observations, ESPRESSO is considered the most precise planet-hunting sensor in operation. It's the successor to HARPS, a similar, but much more limited instrument.

它的确认来自于新一代的光谱仪ESPRESSO，它被安装在智利的一个非常大的望远镜上，这个望远镜的名字很贴切。ESPRESSO是用于岩石系外行星和稳定光谱观测的梯形光谱仪的简称，被认为是运行中最精确的行星探测传感器。它是竖琴的后继者，竖琴是一种类似的乐器，但功能有限得多。

"We were already very happy with the performance of HARPS, which has been responsible for discovering hundreds of exoplanets over the last 17 years," Francesco Pepe, the University of Geneva astrophysicist who heads the ESPRESSO program, explains in a press release.

负责ESPRESSO项目的日内瓦大学天体物理学家弗朗西斯科·佩佩在一份新闻稿中解释说:“我们对HARPS的表现已经非常满意，它在过去17年里发现了数百颗系外行星。”

"We're really pleased that ESPRESSO can produce even better measurements, and it's gratifying and just reward for the teamwork lasting nearly 10 years."

“我们真的很高兴ESPRESSO可以产生更好的测量结果，这是令人满意的，也是对持续近10年的团队合作的回报。”

ESPRESSO can measure the radial velocity of stars like Proxima Centauri with an accuracy of 11.8 inches per second — sensitive enough to determine if a star has any rocky planets in its entourage.

ESPRESSO可以测量像比邻星这样的恒星的径向速度，精度为11.8英寸/秒，足够灵敏，可以确定恒星周围是否有岩石行星。

And sure enough, when trained on Proxima Centauri, ESPRESSO sniffed out a promising planet. Although it's a lot closer to its host star than Earth is our own sun, it basks in about the same amount of energy. That means its surface temperature could be comparable, which in turn, raises the possibility that water flows there.

果然，当在比邻星上训练时，ESPRESSO发现了一颗大有希望的行星。虽然它比地球离太阳更近，但它吸收的能量和太阳差不多。这意味着它的表面温度可以比较，这反过来提高了水在那里流动的可能性。

But there's a catch. Proxima Centauri isn't like the sun we know. As a red dwarf, it's constantly radiating X-rays — several hundred times more than what we receive here on Earth.

但有个问题。比邻星不像我们所知的太阳。作为一颗红矮星，它不断地发出x射线——比我们在地球上接收到的还要多几百倍。

If there's life on Proxima b, it has found a way to overcome that steady bombardment. Or, as the researchers, suggest, the planet itself may have developed its own X-ray shielding atmosphere.

如果比邻星上有生命，它已经找到了一种克服持续轰击的方法。或者，正如研究人员所说，行星本身可能已经形成了自己的x射线屏蔽大气层。

"Is there an atmosphere that protects the planet from these deadly rays?" study co-author Christophe Lovis muses in the release. "And if this atmosphere exists, does it contain the chemical elements that promote the development of life (oxygen, for example)? How long have these favourable conditions existed?"

研究报告的合著者克里斯托弗·洛维斯在新闻稿中沉思道:“是否有大气层保护地球免受这些致命射线的伤害?如果这种大气存在，它是否含有促进生命发展的化学元素(例如氧气)?这些有利条件存在多久了?”

While Earth-like planets are being discovered with increasing frequency — thanks to new, more powerful telescopes and sensory equipment — the confirmation of Proxima b is a particularly exciting development.

由于新的、更强大的望远镜和感官设备的出现，类地行星被发现的频率越来越高，而Proxima b的确认是一个特别令人兴奋的进展。

Mostly because it's so close — just 4.2-million light-year rocket ride away. And also because it points to even more exciting discoveries in the future, thanks to ESPRESSO's planet-hunting prowess.

主要是因为它离我们很近，只有420万光年的火箭飞行距离。同时也因为它指出了未来更令人兴奋的发现，这要归功于ESPRESSO的行星搜寻能力。

"ESPRESSO has made it possible to measure the mass of the planet with a precision of over one-tenth of the mass of Earth," Nobel-Prize-winning physicist Michel Mayor notes in the release. "It's completely unheard of."

诺贝尔奖得主、物理学家米歇尔·马约尔在新闻稿中写道:“ESPRESSO使测量地球质量的精度超过地球质量的十分之一成为可能。这完全是闻所未闻。”