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系外卫星可能正在形成

来源:可可英语 编辑:Melody   可可英语APP下载 |  可可官方微信:ikekenet

Thanks to CuriosityStream for supporting this episode of SciShow Space!

本期节目由CuriosityStream赞助播出!

Go to CuriosityStream.com/Space to learn more.

可以去它的官网CuriosityStream.com/Space了解更多内容哦。

Every now and then, astronomers give us an image of space that just sort of makes our jaws drop.

有时候,宇航员从太空中发回的图像会让我们大吃一惊。

And another one of those images was published last week in the Astrophysical Journal Letters.

上周,《天体物理杂志通讯》上就发布了这样一张图像。

This is an image of a star about 370 light-years away.

这张图像上是距离我们近370光年远的一颗恒星。

See that little spot on the right edge of the disk? That's a new, growing exoplanet.

看到圆盘右侧边缘上的小圆点了吗?那是一颗新出现的系外行星,还在不断膨胀扩大的过程中。

And hiding in the light area around it is something scientists have never conclusively imaged before: a circumplanetary disk.

而隐藏在这颗行星附近发光区域的是科学家从未拍摄到过的——环绕行星的圆盘。

This is the cloud of stuff that the planet is pulling from in order to grow, and someday, if it hasn't already, the leftover material in it will likely collapse to form moons.

这是云状物,该行星从它身上吸食物质从而使自己变大。现在可能其中余下的物质已经坍缩并形成了许多卫星,就算现在还没,总有一天会的。

The fact that we can see this from trillions of kilometers away is mind-blowing, but it also has a lot to teach us about how planets and moons form.

虽然它距离我们数万亿英里远,但它让我们了解到的信息是十分令人兴奋的,而且它也让我们对行星和卫星的形成方式有了更多的了解。

This star is dubbed PDS 70. It's about 5 million years young, and it has at least two Jupiter-sized planets, the second of which was announced just last month.

这颗恒星名为PDS 70,已经形成500万年了,它有2颗跟木星一样大小的星行星,其中第二颗行星是上个月宣布发现的。

The first planet we found orbits about as far away as Uranus is from our Sun, and this new, second planet is about where Neptune would be.

第一颗行星的轨道高度大概有天王星距离太阳那么远,第二颗的位置跟海王星很近。

It's called PDS 70 c, and it's the planet that's been causing all the excitement.

它的名字叫PDS 70 c,它就是那个让我们为之兴奋的新发现。

Initially, though, scientists weren't just focusing on this world.

不过,一开始,科学家还没注意到它。

Instead, they were trying to study both planets, along with the disk of stuff they formed from.

当时他们在努力研究2颗行星以及它们形成过程中赖以吸食的星盘。

To do that, they re-analyzed some data taken by a suite of Chilean telescopes called ALMA.

为了研究,他们重新分析了智利阿塔卡玛毫米/亚毫米波阵列望远镜,

And they found something pretty amazing. There was a noticeable clump of stuff right where PDS 70 c is located.

并有了惊人的发现。PDS 70 c形成的地方有明显的一块物质。

And the signal was brighter than astronomers expected.

而且信号比天文学家预计的还要亮。

Combining that observation with both optical and infrared data from other telescopes, the team concluded there must be a circumplanetary disk around PDS 70 c.

科学家将这一观测结果与其他望远镜获得的光学数据和红外数据放在一起分析,得出了结论——PDS 70 c附近一定有环绕行星的圆盘。

Now, although this image does look pretty clear, it's important to know that it doesn't actually show the disk itself.

虽然这张图像不是十分清晰,但有一点很重要——我们知道图像上并不只是圆盘本身。

The disk is too small and too far away, so this picture just shows the general region around it.

圆盘太小了,离我们又太远,所以这张图像只显示出了其附近的大概区域。

But astronomers are really good at pulling information out of smudgy images, which is why they're so confident that the disk is actually there, and why they can say they've conclusively imaged it.

不过,科学家们很擅长从清晰度低的图像中获取信息,正因如此,他们确信该圆盘就在那里,也正因如此,他们仿佛看到了该圆盘一般地笃定它就在那里。

Regardless, this was awesome news partly because it can teach us about the planet.

不管怎么说,这条新闻让人激动的部分原因是——我们了解了这颗行星。

For example, using some assumptions based on current planetary formation models, astronomers were able to estimate the amount of dust in the disk.

比如,通过假设并基于当前行星组成的一些模型,科学家就能够估测圆盘中的尘埃总量。

It's between 0.2 and 0.4 percent the mass of Earth.

这个量大概在地球质量的0.2-0.4之间。

Also, one data point suggests that hydrogen gas is still falling from the disk onto the planet, which means it's not done growing!

此外,有一个数据点表明:该行星依然在从这个圆盘上吸食氢气,这也表明该行星还在膨胀扩大的过程中!

Then there's the whole moon thing. Because some of that disk material won't join the planet: If it hasn't already, it'll clump together into a multi-moon system, like those we see around Jupiter and the other gas giants.

此外还有关于卫星的发现。由于圆盘的部分物质无法融入行星:如果还未结束,就会聚集在一起,形成多卫星体系,就像我们在木星等气体巨星附近看到的一样。

Most of the moons will be potato-shaped, but we could also get a small spherical body or two.

大多数卫星都是土豆形状的,但也有一两个小球星的。

There's a lot to unpack here, but one of the best parts is that this image isn't only important for understanding this one specific planet: It'll also help us learn more about how solar systems form in general.

这里还有很多信息有待揭开,但最好的一个地方在于——该图像不只对于理解这颗特定的行星有意义,它还能帮助我们了解更多有关太阳形成方式的信息。

Because, maybe surprisingly, this isn't something we totally understand yet.

因为,或许我们会惊讶地发现,自己还并不完全了解它。

Collecting more data about PDS 70 c will help teach us how gas and dust collect around large planets in their early years, and how circumplanetary disks interact with the disks around stars.

收集有关PDS 70 c的更多数据能帮助我们了解大型行星附近的气体和尘埃是如何帮助它们扩大自身的,以及环绕行星的圆盘是如何与恒星附近的圆盘互动的。

This information might even help us understand our own solar system, since we have some big gas giants of our own.

该信息或许还能帮助我们了解太阳系本身,因为太阳系也有一些大型气体巨星。

Speaking of, not all astronomers are studying Jupiter-like planets: Some researchers are studying the real deal.

说到这里就想说两句:并不是所有科学家都在研究跟木星相似的行星:一些科学家在研究木星本身。

Understanding Jupiter can teach us why our solar system looks the way it does.

了解木星可以让我们知道太阳系为什么看起来是这个样子。

But also, studying this planet is cool in its own right.

而且研究木星这个行为本身就很酷。

And last week in Nature Astronomy, the world learned something new about its auroras.

上周,在《自然天文学》上,有一篇文章介绍了与极光有关的内容。

According to a new study, these light shows aren't just more intense than Earth's, they're also powered very differently.

根据这项最新研究,极光不只是强度比地球大而已,连其发光的方式也是与众不同的。

Jupiter is the fastest-spinning planet in our solar system, making one rotation about every ten Earth hours.

木星是太阳系里转速最快的行星,地球每10小时,它就能转一圈。

That means its magnetic field rotates really fast, and it generates a force that actually steals charged sulfur compounds off of its closest spherical moon, Io.

也就是说,木星的磁场转速也非常快,其所产生的磁力可以从其附近最近的卫星——木卫一上吸食带电硫化物。

When charged particles move, they generate a current. And this electric current is kind of a big deal on Jupiter.

带电粒子发生移动时,就会产生电流。这个电流对木星而言意义重大。

It directs electrons toward the planet's upper atmosphere, and those electrons interact with atmospheric particles and make a pretty UV aurora.

这股电流可以让电子流向木星的上层大气层,还会与大气层中的粒子发生反应,产生紫外线极光。

Generally speaking, this is about the same way auroras form here on Earth, although our charged particles come mostly from the Sun and not from the Moon.

总体来说,跟地球上的极光差不多,不过,地球上的带电粒子大多来自太阳,而不是月亮。

But it turns out that the electric currents around Jupiter are different than the ones here at home.

不过,我们最后发现,木星附近的这股电流跟地球上的不同。

Scientists discovered this by studying something called Birkeland currents.

科学家发现这一点是通过研究一种叫白克兰的电流。

These are electric currents that flow along a planet's magnetic field lines.

这种电流会沿着一颗行星的磁场线流动。

They connect the outer regions of the magnetic field with part of the upper atmosphere, and they move both towards and away from the planet's poles.

可以将磁场的外部区域与上部大气层部分相连,会向行星两极做两种方向的运动。

Both Earth and Jupiter have them, and on Earth, you can sort of visualize them as two concentric sheets carrying a direct current that flows in one direction.

地球和木星上都有,而且在地球上,可以将它们可视化为2个同轴的东西,上面有向某一方向流动的直流电。

Birkeland currents play a big role in Earth and Jupiter's auroras, so it makes sense that scientists would want to learn more about them.

白克兰电流对地球和木星的极光而言意义重大,这也说得通科学家为什么想对他们了解更多了。

Specifically, when Birkeland currents carry newly-arrived charged particles, they cause perturbations in a planet's magnetic field.

具体来说,它携带带电粒子,会引起行星磁场的扰动。

And recently, astronomers were able to measure those perturbations around Jupiter using NASA's Juno spacecraft.

最近,科学家可以通过NASA的朱诺飞行器来测量这种扰动了。

In this new study, they calculated the strength of the currents around Jupiter.

在这项新研究中,科学家计算了木星附近电流的强度。

And they found a total electric current of anywhere from 6 million to 91 million amperes depending on the pole and the time of year.

他们发现,强度在600万-9100万之间,这取决于两极以及时节。

系外行星

Compared to Earth's 2-5 million amperes from its Birkeland currents, that's a lot, but it actually isn't as strong as models predicted.

地球上的电流强度在200万-500万之间,所以白克兰电流的强度很大了,但不如模型预测的那么大。

And that's important. Because originally, those models were based on how Birkeland currents work on Earth.

这也很重要,这是因为一开始,这些模型是基于白克兰电流在地球上的工作方式。

They assumed things were the same on Jupiter, so we could just extrapolate what we see here to the planet down the block.

他们假设地球是木星,然后去做相应的推测。

So if those models don't match, it must mean something different is happening inside Jupiter to cause its auroras.

所以,如果模型不适用的话,就说明木星内部有什么与众不同之处,所以极光才不同。

That something, the team hypothesizes, is lots of small areas of turbulence, basically, charged particles zooming around that create not direct currents, but alternating currents that occasionally change direction.

该团队假设,这个东西是许多小区域的扰动,也就是带电粒子到处流动,产生的不是直流电,而是交流电,而且交流电会改变方向。

So instead of current sheets, there's like a bunch of filaments.

所以,它们并不是直流电,而是像白炽灯那种感觉。

That would cause weaker measured perturbations, but if you had enough of them, they would generate the most powerful auroras in the solar system.

这会导致测量的扰动更弱,不过,如果量足够大,就会产生太阳系里强度最大的极光。

So this is yet another example of how we can't always use Earth as a template when trying to study the universe.

这也再次证明我们不能总是以地球为模板去研究整个宇宙。

We have to keep exploring the diversity that's out there, from giants like Jupiter to distant potential exomoons.

我们必须要一直关注多样性,无论是木星还是遥远的系外卫星。

Only then will we be able to put together a big, accurate picture of space.

只有这样,我们才能对宇宙有全面精准的认识。

This episode of SciShow Space News is brought to you by CuriosityStream.

本期节目由CuriosityStream赞助播出。

It's a subscription streaming service that offers more than 2400 documentaries and nonfiction titles, including some exclusive originals.

这是一款可订阅的流媒体服务,可以提供2400多个纪录片和非虚构类影片,有很多都是独家原版哦。

And it's a great place to learn more about space.

这里是了解太空的好地方。

Like, there's a series called Destination: Pluto about a mission we've talked about a lot: the New Horizons mission to Pluto.

比如,其中有一个系列叫做《目的地:冥王星》,内容关于我们已经多次提过的一个任务——新视野号飞往冥王星。

It tells you more about why Pluto is so important and even has interviews with the team who made the spacecraft.

这期节目中,我们可以了解到为何冥王星如此重要,甚至可以看到新视野号研究团队的采访。

If you want to check it out, you can get unlimited access to CuriosityStream starting at just $2.99 per month.

如果你想了解的话,可以从每月2.99美元的初始低价开始订阅哦,可以无限浏览。

And for SciShow Space viewers, the first 31 days are totally free if you sign up at curiositystream.com/space and use the promo code space.

我们节目的粉丝前31天是免费的,只需要注册一下,并使用优惠码space即可。

We hope you learn something new!

希望大家都能有所得!

重点单词   查看全部解释    
occasionally [ə'keiʒənəli]

想一想再看

adv. 偶尔地

 
noticeable ['nəutisəbl]

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adj. 显而易见的

 
initially [i'niʃəli]

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adv. 最初,开头

 
intense [in'tens]

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adj. 强烈的,剧烈的,热烈的

联想记忆
pole [pəul]

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n. 杆,柱,极点
v. (用杆)支撑

 
generate ['dʒenə.reit]

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vt. 产生,发生,引起

联想记忆
planet ['plænit]

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n. 行星

 
calculated ['kælkjuleitid]

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adj. 计算出的;适合的;有计划的 v. 计算;估计;

 
planetary ['plænitəri]

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adj. 行星的,有轨道的

 
extrapolate [eks'træpəleit]

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v. 预测,推测

联想记忆

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