天文學(xué)家在遙遠(yuǎn)的太陽系中發(fā)現(xiàn)了一個(gè)熟悉的特征

天文學(xué)家在遙遠(yuǎn)的太陽系中發(fā)現(xiàn)了一個(gè)熟悉的特征

How typical is our Solar System? The question bedevils planetary scientists, but making detections of analogous features in other planetary systems is pretty hard. Yet astronomers have just made one - of a Kuiper belt-like feature around a star 320 light-years away.

我們的太陽系有多典型?這個(gè)問題困擾著行星科學(xué)家，但要在其他行星系統(tǒng)中探測類似的特征是相當(dāng)困難的。然而天文學(xué)家們剛剛在320光年外的一顆恒星周圍形成了柯伊伯帶狀的一個(gè)特征。

It is, they say, the first polarimetric detection of the inner ring circling the star we call HD 141569A. And it's revealing new details about a crucial period of planetary development.

他們說，這是第一次對(duì)環(huán)繞恒星的內(nèi)環(huán)進(jìn)行偏振探測，我們稱之為HD 141569A，它揭示了行星發(fā)展關(guān)鍵時(shí)期的新細(xì)節(jié)。

HD 141569A is actually a pretty interesting and well-studied object. It has two companions in a trinary system, both red dwarfs. But HD 141569A is just 5 million years old, around three times the mass of the Sun, of a blue spectral type burning hot and bright.

HD 141569A實(shí)際上是一個(gè)非常有趣的研究對(duì)象。它有兩個(gè)同伴，都是紅矮星。但HD 141569A只有500萬年的歷史，大約是太陽質(zhì)量的三倍，是一種熾熱明亮的藍(lán)色光譜類型。

In 1999, a disc was discovered around the young star, with two rings peaking at 220 and 360 astronomical units, respectively. These are the remnants of material that swirled around and accreted into the star as it was forming; over time, bits of material start sticking to each other, accreting into planets.

1999年，在這顆年輕恒星周圍發(fā)現(xiàn)了一個(gè)圓盤，兩個(gè)環(huán)的峰值分別為220和360天文單位。這些是在恒星形成的過程中旋轉(zhuǎn)并吸積到恒星中的物質(zhì)的殘余;隨著時(shí)間的推移，一些物質(zhì)開始相互粘著，吸積到行星中。

In HD 141569A's disc, a gap between the two rings suggested that a planet was forming, gravitationally hoovering up all the material in its orbit.

在HD 141569A的圓盤中，兩個(gè)環(huán)之間的間隙表明一顆行星正在形成，在引力作用下吸走了其軌道上的所有物質(zhì)。

Here in the Solar System, we also have remnants of the Sun's accretion disc from its formation 4.6 billion years ago. We call it the Kuiper belt, and it's a puffy disc of icy debris out beyond the orbit of Neptune. Pluto, at an average distance of 39.5 astronomical units, is in the Kuiper belt.

在太陽系中，我們也有46億年前太陽吸積盤形成的殘余。我們稱之為柯伊伯帶，它是海王星軌道外一個(gè)膨脹的冰碎片盤。冥王星位于柯伊伯帶，平均距離為39.5個(gè)天文單位。

Towards the end of this planetary accretion process, what is left is known as a debris disc, and it can extend hundreds of astronomical units across. The disc around HD 141569A is a hybrid - it's in transition between a protoplanetary disc and a debris disc.

在這個(gè)行星吸積過程接近尾聲時(shí)，剩下的被稱為碎片盤，它可以延伸數(shù)百個(gè)天文單位。HD141569A周圍的圓盤是一個(gè)混合體，它在原行星圓盤和碎片圓盤之間過渡。

Hybrid discs are fascinating to planetary scientists, since they can tell us about how gas giants form, and how growing planetesimals interact with the gas and dust in the disc.

混合圓盤對(duì)行星科學(xué)家很有吸引力，因?yàn)樗鼈兛梢愿嬖V我們氣態(tài)巨行星是如何形成的，以及成長中的星體是如何與圓盤中的氣體和塵埃相互作用的。

Now, by studying scattered and twisted electromagnetic radiation from the region around the star, astronomers led by Juan Sebastian Bruzzone of The University of Western Ontario in Canada have imaged a similar ring around HD 141569A, peaking at a distance of 44 astronomical units from the star.

現(xiàn)在，加拿大安大略大學(xué)的胡安·塞巴斯蒂安·布魯佐內(nèi)(Juan Sebastian Bruzzone)領(lǐng)導(dǎo)的天文學(xué)家通過研究恒星周圍區(qū)域散射和扭曲的電磁輻射，在HD 141569A附近成像出一個(gè)類似的環(huán)，在距恒星44個(gè)天文單位的距離處達(dá)到峰值。

And they have found not just evidence of planetary formation, but hints that there's another ring structure in the disc closer to the star.

他們不僅發(fā)現(xiàn)了行星形成的證據(jù)，而且還發(fā)現(xiàn)了在離恒星較近的圓盤中有另一個(gè)環(huán)結(jié)構(gòu)的跡象。

Specifically, they found a spiral arm - a feature found in a few other protoplanetary discs, including the two outer rings of HD 141569A, and taken to be the evidence of a forming planet. Based on the features of the spiral arm, the researchers inferred the planet would be around Jupiter's mass or slightly smaller.

具體地說，他們發(fā)現(xiàn)了一個(gè)螺旋臂，這是在其他一些原行星盤中發(fā)現(xiàn)的特征，包括HD 141569A的兩個(gè)外環(huán)，被認(rèn)為是行星形成的證據(jù)。根據(jù)旋臂的特征，研究人員推斷這顆行星可能在木星的質(zhì)量附近或稍小一些。

They also compared their observed emission to models to find the best fit for the type of dust that could have produced it. But, even with the best-fit models, there was emission that couldn't be accounted for.

他們還將觀測到的排放量與模型進(jìn)行了比較，以找到最適合可能產(chǎn)生這種排放的粉塵類型的排放量。但是，即使是最合適的車型，也有無法解釋的排放。

However, when another ring located closer to the star was added to the calculations, this solved the problem. A belt between 5 and 15 astronomical units reproduced the emission beautifully.

然而，當(dāng)另一個(gè)靠近恒星的環(huán)被加入到計(jì)算中時(shí)，這個(gè)問題就解決了。一條5到15個(gè)天文單位之間的帶完美地再現(xiàn)了輻射。

Aside from the fact that it's pretty danged amazing that astronomers can even achieve such a detection, this is the sort of finely detailed study that can tell us how planets are born.

除了天文學(xué)家甚至可以實(shí)現(xiàn)這樣的探測，這是一個(gè)相當(dāng)驚人的懸而未決的事實(shí)之外，這是一種非常詳細(xì)的研究，可以告訴我們行星是如何誕生的。

In turn, that can tell us more about our own Solar System - and knowing how normal or unusual it is can help us figure out how the heck we got here at all.

反過來，這可以告訴我們更多關(guān)于我們自己的太陽系的信息——知道它有多正?；虿粚こ？梢詭椭覀兏闱宄覀兊降资窃趺磥淼竭@里的。

"Considering resolved imaging data from other high-contrast facilities, the HD 1415169A debris disc shapes up to be made of at least three, and potentially four nested rings, with spiral structures on the three spatially resolved rings," the researchers wrote in their paper.

研究人員在論文中寫道：“考慮到來自其他高對(duì)比度設(shè)施的分辨率成像數(shù)據(jù)，HD 1415169A碎片盤的形狀至少由三個(gè)環(huán)組成，可能有四個(gè)嵌套環(huán)，三個(gè)空間分辨率環(huán)上有螺旋結(jié)構(gòu)。”。

"As such, it is an excellent laboratory for studying dynamically perturbed discs."

“因此，這是一個(gè)研究動(dòng)態(tài)擾動(dòng)盤的優(yōu)秀實(shí)驗(yàn)室。”

The research has been accepted into The Astronomical Journal, and is available on arXiv.

這項(xiàng)研究已被《天文雜志》接受，可在arXiv上查閱。