我們發(fā)現(xiàn)了三顆巖石系外行星

我們發(fā)現(xiàn)了三顆巖石系外行星，它們圍繞著一顆12光年外的恒星運(yùn)行

Three new exoplanets have been found orbiting a nearby star, and one of them is ranked pretty highly for potential habitability.

三顆新的系外行星圍繞著附近的一顆恒星運(yùn)行，其中一顆行星的潛在宜居性非常高。

All three are rocky, and within the vicinity of Earth-sized - and the outermost is orbiting the star in the habitable zone, where temperatures are compatible with the possibility of liquid water on the surface.

這三顆行星都是巖石構(gòu)成的，而且都在地球大小的范圍內(nèi)——最外層是圍繞恒星運(yùn)行的宜居帶，那里的溫度與表面液態(tài)水存在的可能性相匹配。

The star is Gliese 1061, at a distance of 3.67 parsecs - around 12 light-years away - making it the 20th closest star to the Solar System. And its three planets are Gliese 1016 b, Gliese 1016 c and Gliese 1016 d.

顆恒星是Gliese 1061，距離為3.67秒秒，大約12光年，是離太陽系最近的第20顆恒星。它的三顆行星是Gliese 1016b, Gliese 1016c和Gliese 1016d。

The research team also found evidence that could indicate a fourth planet, but ultimately ruled it out as stellar activity. The findings are reported on preprint server arXiv, and have been submitted to the Monthly Notices of the Royal Astronomical Society.

研究小組還發(fā)現(xiàn)了可能存在第四顆行星的證據(jù)，但最終排除了它是恒星活動的可能性。這些發(fā)現(xiàn)已在預(yù)印本服務(wù)器arXiv上發(fā)表，并已提交給英國皇家天文學(xué)會(Royal Astronomical Society)的月報。

Gliese 1061 is a red dwarf. These stars are cool and faint, which means their habitable zone is a lot closer to the star than a hotter, brighter star - like the Sun, for instance. And planets orbiting their stars closely are easier to find than stars much farther out.

格利澤1061是一顆紅矮星。這些恒星又冷又暗，這意味著它們的宜居帶比更熱、更亮的恒星(比如太陽)離恒星更近。而且，與距離較遠(yuǎn)的恒星相比，距離較近的行星更容易被發(fā)現(xiàn)。

This makes them a great target for habitable exoplanet searches, but that doesn't mean they're necessarily hospitable.

這使得它們成為尋找宜居系外行星的絕佳目標(biāo)，但這并不意味著它們一定適合居住。

Red dwarfs are often restless and wild, lashing the space around them with stellar flares.

紅矮星通常是不安分和狂野的，用恒星耀斑猛烈地沖擊著它們周圍的空間。

Such is the case with Proxima b, the rocky exoplanet found orbiting in the habitable zone of our nearest stellar neighbour, Proxima Centauri.

比鄰A B就是這樣一個例子，它是一顆多巖石的外行星，在我們最近的恒星鄰居比鄰A半人馬座的可居住區(qū)域中被發(fā)現(xiàn)。

Gliese 1061 is a lot like Proxima Centauri, but there is one key difference: it's a heck of a lot quieter. Which means - you guessed it - potentially higher chances of habitability.

Gliese 1061很像比鄰星，但有一個關(guān)鍵的區(qū)別:它要安靜得多。這意味著——你猜對了——潛在的更適合居住的機(jī)會。

All three planets were detected using the radial velocity, or "wobble", method.

所有三顆行星都是用徑向速度(或稱為“擺動”)方法探測到的。

While many exoplanets are identified by looking at dips in light as the planets pass between us and their star (the transit method), in this instance, the stars' orbits are angled so that they never pass between us and the star. That means we have to detect them using gravity.

雖然許多系外行星是通過觀察行星在我們和它們的恒星之間運(yùn)行時的光線變化來確定的(凌日法)，但在這種情況下，恒星的軌道是有角度的，因此它們永遠(yuǎn)不會在我們和恒星之間運(yùn)行。這意味著我們必須利用重力來探測它們。

You see, although it seems like a star might be more or less fixed in position, the planet and the star actually orbit a mutual centre of gravity. This is usually inside the star, since it is so much more massive than its planets, but the tug of the planet is enough to pull the star just ever-so-slightly off-centre as it moves around.

你看，雖然看起來恒星或多或少固定在某個位置上，但行星和恒星實際上繞著一個相互的重心運(yùn)行。這通常是在恒星內(nèi)部，因為它比行星要大得多，但是行星的引力足以使恒星在移動時稍微偏離中心。

If you have precise enough detection methods - which we do - this wobble can be used not just to infer the presence of a planet (or several planets), but to calculate their mass, based on how much the star is wobbling.

如果你有足夠精確的檢測方法——我們有——這種擺動不僅可以用來推斷行星(或幾個行星)的存在，而且可以根據(jù)恒星擺動的程度來計算它們的質(zhì)量。

This returned some pretty interesting masses for Gliese 1061's planets. Gliese 1016 b - the innermost planet - is 1.38 times the mass of Earth. The middle planet, Gliese 1016 c, is 1.75 times the mass of Earth. And the outermost planet, Gliese 1016 d, is 1.68 times the mass of Earth.

這為Gliese1061的行星返回了一些相當(dāng)有趣的質(zhì)量。最里面的行星gliese 1016 b是地球質(zhì)量的1.38倍。中間的行星gliese 1016 c是地球質(zhì)量的1.75倍。最外層的行星gliese 1016 d是地球質(zhì)量的1.68倍。

This is also how we infer the planets are rocky, since those masses are rarely seen in gaseous exoplanets.

這也是我們推斷行星是多巖石的原因，因為這些質(zhì)量在氣態(tài)系外行星中很少見到。

All three planets orbit the star much closer than any of the Solar System's planets. Gliese 1016 b whips round every 3.1 days; Gliese 1016 c every 6.7 days; and Gliese 1016 d every 13 days. The star is so cool that these orbits place Gliese 1016 d in the habitable zone, and Gliese 1016 c is right on the innermost cusp of the habitable zone.

所有三顆行星圍繞恒星運(yùn)行的軌道都比太陽系的任何一顆行星都要近得多。Gliese 1016 b每3.1天旋轉(zhuǎn)一次;Gliese 1016 c每6.7天;格利澤1016 d每13天。這顆恒星是如此的冷，以至于這些軌道將Gliese 1016d置于宜居帶，而Gliese 1016c正好位于宜居帶的最深層。

Of course, this doesn't mean life is waiting for us to find it just 12 light-years away.

當(dāng)然，這并不意味著生命正等著我們在12光年之外找到它。

As the researchers note, the star may be relatively quiet now, but it probably was quite active in its recent past. If it has been bathing its planets in stellar radiation, any life that was there is unlikely to have survived.

正如研究人員所指出的，這顆恒星現(xiàn)在可能相對比較安靜，但在它最近的過去可能相當(dāng)活躍。如果它一直將行星沐浴在恒星輻射中，那里的任何生命都不太可能存活下來。

But it does add to the tally of rocky planets in nearby space. According to the Exoplanet Archive, somewhere in the vicinity of 70 exoplanets have been located within 10 parsecs (32.6 light-years) of the Solar System, many of them small and possibly rocky.

但它確實增加了附近太空中巖石行星的數(shù)量。根據(jù)系外行星檔案，大約有70顆系外行星位于距太陽系10秒(32.6光年)的范圍內(nèi)，其中許多都很小，可能是巖石構(gòu)成的。

And just a couple of months ago, astronomers revealed the presence of two Earth-like planets orbiting Teegarden's star 12.5 light-years away. With at least half of all red dwarf stars thought to have rocky planets, our local neighbourhood suddenly seems quite bustling, really.

就在幾個月前，天文學(xué)家們發(fā)現(xiàn)了兩顆類地行星的存在，它們圍繞著蒂加登12.5光年遠(yuǎn)的恒星運(yùn)行。至少有一半的紅矮星被認(rèn)為有巖石行星，我們的鄰居突然變得非常熱鬧，真的。

The research has been submitted to the Monthly Notices of the Royal Astronomical Society, and is available on arXiv.

這項研究已提交給英國皇家天文學(xué)會的月報，可在arXiv上找到。