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In 1849, we discovered an object between Mars and Jupiter called Hygiea.
1849年，我们发现火星和木星之间存在一个叫健神星的物体。
For a while, we thought it was just another big asteroid in the asteroid belt,
有那么一段时间里，我们以为这个物体只是小行星带里另一个比较大的小行星罢了。
but on Monday, a team announced in Nature Astronomy that it might actually deserve a different title.
但是周一的时候，一个团队在《自然天文学》上宣布它应该有另一个更合适的称号。
Based on their observations, Hygiea is probably a dwarf planet!
根据他们的观察，健神星很有可能是一颗矮行星。
And it might also have a different origin story than once thought.
而且健神星的起源可能和我们曾经想的不一样。
The requirements for being a dwarf planet are pretty simple:
成为矮行星的条件相当简单：
You need to orbit only the Sun, be massive enough that your gravity pulls you into a roughly spherical shape, and not be able to clear your orbit.
必须只能环绕太阳飞行、质量足够大（这样引力才能拉动该物体变成大概是球形的形状），才能通过轨道。
In other words, your gravity has to be weak enough that you can't push similarly-sized objects out of your path.
换言之，引力作用要非常小，小到该物体不能将同样大小的物体推出轨道。
As a relatively light object living in the asteroid belt, Hygiea already checked two of these boxes.
健神星是小行星带里质量相对轻的物体，符合上述2个条件。
But until now, we couldn't tell whether it was spherical, because we were busy looking at other things, and because it's very dark and hard to see.
不过，直到目前位置，我们都无法判断健神星的形状是否是圆形的，因为我们忙着观测其他事情，也因为这里十分暗，很难看清。
Then came this week's big announcement!
然后，本周的重大消息来了！
To make the new discovery, astronomers used the European Southern Observatory's Very Large Telescope to get the best images yet of Hygiea.
为了实现这个新发现，天文学家用到了欧洲南方天文台的甚大望远镜，用它的目的是获得健神星的最佳图像。
And we can now say for sure that it is really round!
现在，我们可以确定健神星就是圆形的了！
That means it checks all the dwarf planet boxes!
也就是说，健神星符合成为矮行星的所有条件！
Though, just to be clear, Hygiea isn't formally a dwarf planet yet some official conversations will need to be had about it first.
不过，目前官方还没有承认健神星是矮行星，因为需要在那之前，需要一些正式的对话才行。
But if it is reclassified, it will officially replace Ceres as the smallest dwarf planet in our solar system.
但如果给健神星重新分类的话，健神星将正式取代谷神星，成为太阳系里最小的矮行星。
So, this is all great; I mean, humans love categorizing things.
这样挺好的，毕竟咱们人类本来就喜欢给事情分类。
But these observations have greater significance for the solar system's history, too.
但这些观测对太阳系历史的意义也很重大。
Because this team didn't just find that Hygiea is spherical.
但该团队不仅发现健神星是球形的，
They also noticed something weird about the object's surface.
他们还发现该物体的表面存在一些奇怪的现象。
Previous research has shown that Hygiea is the largest member in a family of asteroids that all formed from the same parent body.
此前有研究发现，健神星和其他一些小行星同为一个母体产生，但健神星却成了最大的那一个。
The working hypothesis has been that this parent body was hit by a bunch of impacts that knocked off smaller asteroids until, eventually, Hygiea was all that was left behind.
一直以来，假说是这样的：这个形成健神星的母体受到了一些冲击的影响后，形成一些更小的小行星。最终，健神星是唯一留存下来的。
Based on this, Hygiea should be covered in big craters.
基于此，健神星表面应该满是巨型火山口。
But the authors of this paper imaged 95% of the thing's surface, and there are no giant craters to be found.
但本文作者提供了健神星表面的图片，而图片显示，其表面并没有巨型火山口。
To solve this new mystery, the authors ran simulations to see what conditions could have led to this scenario.
为了解决这个新谜团，本文作者进行了一些模拟，他们想要看看是什么原因导致了这种情况。
And they suggested the original parent body didn't survive all those impacts after all.
他们认为，一开始的母体还没有完整经历所有冲击就消失了。
Instead, the impacts were likely so big that the parent body was totally destroyed!
而且，由于冲击太过强烈，所以母体被彻底破坏了！
Lots of the pieces just went flying off to form all of the smaller asteroids in the family, but enough were big and close enough that they reformed into Hygiea!
其分裂而成的许多碎片飞散，形成了健神星的兄弟姐妹，只是体型没健神星庞大。但最后，由于积攒了足够多的碎片，健神星形成了！
So, keep an eye out for an official announcement, and maybe we'll get to categorize Hygiea as a dwarf planet soon.
所以，我们还是敬请关注官宣吧。或许健神星不久后就会被归类为矮行星。
And speaking of big collisions… In 2017, scientists had the chance to directly observe something amazing for the first time: the collision of two neutron stars.
说起大型碰撞……2017年，科学家有机会首次直接观测让人惊奇的现象：2颗中子星相撞。
Neutron stars are incredibly dense, neutron-rich objects, and it's normally really hard to see what happens when they run into each other.
中子星密度极高，富含中子，所以，正常情况下，很难看到它们彼此相撞会发生什么。
Partly because the events are pretty rare, and partly because there aren't any neutron stars around here.
这其中的部分原因是：发生事件的几率很小；还有部分原因是：这附近没有什么中子星。
But we finally got a chance to do it when two stars collided only 130 million light-years away.
不过，机会还是来了——有2颗恒星在仅距离我们1.3亿光年远的地方相撞了。
Which in astronomy terms, is much closer than it sounds.
在天文学里，这个距离是很短的。
Last Wednesday in the journal Nature, one team published their analysis of data from that collision.
上周三，《自然》杂志上，一组团队发布了他们关于这次撞击的数据分析。
And they found the best evidence yet of something we've suspected for a long time:
他们发现：我们长期以来怀疑很久的事情得到了实锤：
Neutron star collisions produce really, really heavy elements.
中子星碰撞会产生质量特大的元素。
So, some context. Stars form elements through nuclear fusion, which is pretty straightforward:
这里分享一些背景信息是：恒星是通过核聚变来形成元素的，这样说是很直接的。
They fuse together lighter elements to create heavier ones.
恒星将质量较轻的元素聚合在一起形成质量更大的元素。
At first, this process just involves turning hydrogen into helium.
起初，这个过程仅包括将氢变成氦。
But over a star's life, as more particles get smashed together, it can make elements as heavy as iron.
但在一颗恒星的生命周期里，随着越来越多的分子搅和在一起，元素就会形成质量很大的铁。
But there are tons of heavier elements out there, like copper and lead, that stars can't make.
但那里有很多很多质量很大的元素，比如铜、铅，这些元素是恒星不能产生的。
The pressures and temperatures inside them just aren't high enough.
他们内部的压力和温度不够高。
So to get these elements, you need something more.
所以，为了获得这些元素，就需要更多的元素。
Traditionally, scientists have believed these atoms come from supernovas:
一直以来，科学家都认为这些原子来自于超新星：
hotter, more powerful explosions that happen when some stars die.
温度更高、威力更大的爆炸，这种爆炸会在恒星消亡时产生。
And that still seems to be true! But according to this new paper, supernovas aren't the only events that make heavy elements: Neutron star collisions can, too.
而现在看来似乎仍是如此！不过，根据这篇新文章，超新星并不是唯一一种会产生特大质量元素的活动：中子星碰撞也可以哦。
In the paper, the team found evidence that the collision was creating the heavy element strontium - a lot of it.
在本文中，该研究团队发现证据表明中子星碰撞可以产生特大质量的锶——而且会产生很多。
In fact, about five Earth masses! They suggest it came from a process called rapid neutron capture.
实际上，锶的质量合起来有5个地球那么多！该团队认为锶产生于一个叫快中子俘获的过程。
Essentially, that's where you have so many neutrons in one place that they just sort of stick to the particles around them.
所以这里会有很多中子聚集，而有很多中子的地方，中子会聚集在附近的粒子上。
So you end up with a bunch of nice, heavy atoms.
所以，最后这里会有许多质量很大的原子形成。
If the atom is unstable, some of those neutrons can break down into protons and electrons.
如果所形成的原子不稳定，那么其中一些中子会分解成质子和电子，
And that leads to heavier elements. This is cool, because we need heavy elements to make things like planets.
继而形成质量更大的元素。这很酷，因为我们需要质量大的元素来形成行星之类的东西。
So knowing that supernovas aren't the only creators out there tells us something valuable about the makeup of the universe.
所以，如果我们知道超新星不是唯一一种能产生特大质量元素的东西，这让我们对宇宙的组成有了宝贵的了解。
And another fun fact: This study officially confirms that neutron stars are actually made of neutron-rich matter.
还有件趣事；该研究正式证实了中子星是由富含中子的物质组成的。
That was another case where we had a lot of math to support that assumption, but no physical confirmation.
这个也是我们用大量数学计算来支持的假设，但目前尚没有在物理学上得到证实。
So, this work provides really clear, hard evidence for two fundamental aspects of astrophysics. You know, no big deal.
所以，他们的研究提供了明确的确凿证据，可以证实天文物理学上2个基本方面。这不是什么大事儿。
Thanks for watching this episode of SciShow Space News!
感谢收看《太空科学秀》！
And an extra-special thanks to this episode's President of Space, Matthew Brant.
要特别对本期粉丝负责人马修·布莱恩特说声感谢。
Matthew is one of our longtime patrons on Patreon one of the people who supports SciShow and helps us keep making content like this.
马修长期以来一直是我们的粉丝，他支持我们的节目，帮助我们做了类似本期的节目。
So, thanks for everything, Matthew! SciShow is so much better because of patrons like you.
马修，感谢你做的一切！《太空科学秀》因为像你这样的粉丝变的更好了。
If you want to learn how to support the show and become our next President of Space, you can go to patreon.com/scishow.
如果你想了解如何支持我们的节目并成为像马修一样的粉丝，可以浏览patreon.com/scishow看看。
