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Just about every galaxy has a supermassive black hole at its center, one millions of times the mass of the Sun.
几乎每个星系中心都有一个超大质量的黑洞，其质量是太阳的近100万倍。
It's been hard nailing down exactly how many smaller black holes there are out there, though, especially near galactic centers, because black holes are hard to see.
不过，很难确定有多少个小黑洞，尤其是在银心附近，因为黑洞是很难观测到的。
But a paper published last week in the journal Physical Review Letters has new insight about where we can look to nail that number down.
但上周《物理评论快报》上发表了一篇论文，这篇论文对可以敲定黑洞数量的观测点有新的看法。
The secret? Black holes of a feather orbit together.
奥秘在于：同一类黑洞会一起运行。
Black holes look… black.
黑洞看起来就是黑色的。
They're so dense that even light can't escape from them, so directly detecting one is nearly impossible.
由于黑洞密度极高，所以即便是光也无法逃脱它的魔爪，所以直接观测几乎是不可能的。
We can still find them through gravitational effects, though, and through X-ray light given off by objects that heat up before falling into them.
不过，我们还是可以根据引力效应来寻找黑洞，也可以根据物体在坠落到黑洞前因温度升高而发出的X光线来寻找黑洞。
But it's been a challenge to use those measurements to estimate how many less massive black holes are out there, ones with masses like the Sun's.
但很难通过这些测量结果来估测小黑洞的数量，比如质量跟太阳差不多的黑洞的数据。
Earlier this year, a study of X-ray sources in the Milky Way suggested that there might be as many as ten or twenty thousand smaller black holes near our galaxy's center.
今年年初，科学家对银河系的X光线来源进行了研究。该研究表明，银心附近小黑洞的数量可能有1-2万个。
And a similar study of ring galaxies, the beautiful results of galactic collisions, found evidence for lots of small black holes, too.
此外，科学家对环星系也做了类似的研究。所谓环星系就是银河系内发生碰撞产生的美丽产物。该研究发现了证据，可以表明银河系中也存在很多小黑洞。
But new simulations have given us a much better idea of where to look for them next.
但新的模拟情况也让我们更加了解下一步去哪里寻找环星系。
In last week's paper, a pair of Hungarian physicists made a new computer model of small stars, heavy stars, and black holes all orbiting near the center of a galaxy like the Milky Way.
在上周的论文中，两位匈牙利物理学家制作了一个新型电脑模型，该模型的组成元素有：小恒星、大质量恒星、环绕银河系等星系中心飞行的黑洞。
They ran their program for millions of simulated years, enough time for everything to finish jostling for position and get settled.
他们运行的项目涵盖了数百万个模拟年。数百万年对于任何物体来说都足以确定位置了。
Once that was all over, they found that low-mass stars ended up with all sorts of orbits, different sizes, different angles, you name it.
等位置确定后，他们发现，低质量恒星最后会有各种各样的轨道，大小不同、角度也不同，总之是什么情况都有。
Together, they created a big, bright sphere of stars around the galactic center, which is pretty much what we see in actual galaxies.
他们一起在星系中心附近创造出了一个由恒星组成的又大又亮的球体，这就是我们在实际星系中能看到的景象。
The black holes, though, did something more interesting.
而黑洞就更有趣了。
All the pushing and shoving before orbits settled down tended to push them all into one plane, a lot like how all the planets in our solar system orbit in a single, flat disk.
轨道确定之前，黑洞之间彼此有推拉的作用力，这些作用力倾向于将它们带入同一个平面，这与太阳系行星在单一的平坦圆盘上运动非常相似。
The same happened to heavier stars, which we've seen in the actual Milky Way.
质量大一些的恒星也会出现同样的情况，这一点，我们在实际的银河系中也可以观测到。
But we didn't know it would happen with black holes, too.
但我们此前并不知道黑洞也会出现这样的情况。
Now, that insight could help target our searches for black holes near the center of the galaxy, learning where they are and what they're doing more quickly than we could through general surveys.
了解了这种情况之后，我们就能在星系附近寻找黑洞时更有目标性，就有助于我们知道黑洞身在何处，并以更快的方式了解到黑洞的行为方式。这是一般调查达不到的。
Meanwhile, in other black hole news, sort of, scientists are getting one step closer to totally understanding supernovas.
与此同时，还有一些与黑洞有关的新闻。比如，科学家对于彻底了解超新星现象又近了一步。
Most black holes form from supernovas: colossal explosions of dying stars that launch heavy elements throughout the universe.
大多数黑洞都是在超新星现象中形成的。所谓超新星，就是即将消亡的恒星发生了大爆炸，在整个宇宙中发射出了许多重元素。
So far, we have a good idea of what happens in the chaos of a supernova, but there are still some details to work out and some measurements we need to make before we're completely confident in our models.
目前为止，我们已经对超新星的一片混沌之中发生了什么比较清楚了，但还有一些细节需要探究，此外还要进行一些测量，才能对模型有十足的信心。
The good news is, a paper in last week's Nature Astronomy has helped us check one item off that list:
好消息是：上周，《自然天文学》上发表了一篇论文，帮助我们确定了一件事：
understanding a small flash before the main explosion.
理解了发生大型爆炸前的一个小型闪光现象。
The paper's authors looked at Type II supernovas.
这篇文章的作者观测的是II型超新星。
These start when a massive star begins to run out of nuclear fuel, and its gravity starts pulling everything in toward its center.
II型超新星形成过程之初是：一颗超大质量的恒星用尽了核燃料，其引力作用开始将其他事物往其中心拉。
As things get denser, protons and electrons in the star's core combine into neutrons, creating an incredibly dense neutron star.
随着密度的升高，恒星内核的质子和电子凝聚在一起形成了中子，从而产生了密度极高的中子星。
Then, when the original star's outer layers collide with the edge of that inner neutron star, they violently bounce off, creating an explosion that can outshine an entire galaxy.
随后，恒星的外层与内部的中子星边缘相撞，开始距离的反弹，从而发生了足以照亮整个星系的爆炸。
Before that main explosion, though, we've also seen a smaller flash.
在这次大型爆炸发生之前，我们还看到了规模较小的闪光现象。
We've only observed them a couple of times, but we think they should happen before pretty much every Type II supernova.
虽然我们仅对这种现象观测过几次，但我们认为这种现象应该是在II型超新星形成之前发生的。
We've just never been able to confirm that, because we haven't had instruments sensitive enough and haven't looked long enough to catch them all.
我们只是一直没能证实这一点，因为我们的设备不够灵敏，观测距离不够远，无法完全收入眼下。
That's where this new paper helped.
而这篇论文却对这种情况有所帮助。
Using a telescope in Chile equipped with one of the highest-resolution cameras in the world, these researchers watched that process unfold on 26 different Type II supernovas.
他们使用了智利的一台望远镜，这台望远镜的清晰度是世界上最高之一。他们观测到这一进程在26个不同的II型超新星上都发生了。
And they found a flash of light before most of the main explosions.
他们发现在大多数大型爆炸发生之前会出现闪光。
That confirmed those flashes are a regular thing.
经确认，这种闪光现象是常规现象。
But then, the authors went further.
不过随后，本文作者研究的更深入了。
We already knew that for thousands of years before a supernova, some of the star's atmosphere leaks into space, leaving a bunch of gas hanging around when the star finally does start collapsing.
几千年前，我们就已经知道超新星发生之前会有闪光现象，我们也知道一些恒星的大气层会流入宇宙中，所以附近就有一些空气，而这颗恒星也开始消亡。
We think the flashes happen when some of the energy from the formation of the neutron star sneaks out and hits this gassy layer before the energy of the rebounding gas does.
我们认为，之所以会发生闪光现象，是因为中子星形成过程中的一些能量会流出来，并且会在反弹气体的能量撞击气体层之前，先一步撞击气体层。
But we haven't had a good idea of how much gas is actually out there because we've seen so few of these flashes.
但我们不太了解究竟有多少气体，因为闪光现象，我们也没见到过几次。
So this paper's authors worked with an existing model of supernovas to figure it out.
所以，本文作者想通过现有的超新星模型来解决这个问题。
They found that, to make the flashes they observed, the star would need to lose as much gas as you'd find in our entire Sun before becoming a Type II supernova.
他们发现，要成为II型超新星，即必须要丢掉我们在太阳内部能发现的气体总量。
Which goes to show you how huge these stars are to begin with.
这样就能看出这些恒星刚开始的时候有多么大。
They're some of the biggest ones in the universe.
是宇宙里排的上名次的那种大。
That's a lot of gas. But it's only enough to create a tiny flash that we hardly noticed before, because it then gets drowned out by the supernova itself.
气体也很多。但即便是这样，也只能产生很小的闪光，我们以前一直都没怎么注意到。因为这种闪光很快就会被超新星所熄灭。
With bigger and better telescopes coming online all the time, and with models that are constantly being improved by research like this, we should be seeing more and more of these flashes as time goes on.
更大、更灵敏的望远镜不断面世，模型也通过这样的研究而越来越精良，所以，以后，我们一定能见证更多的闪光现象。
And that means we should gain a better and better understanding of what happens in some of the universe's largest explosions.
也就是说，我们会对宇宙最大规模的一些爆炸现象有越来越准确的了解。
Thanks for watching this episode of SciShow Space News!
感谢收看本期的《太空科学秀》！
There's a lot happening in the universe, and if you want to learn about the latest news in planets, moons, black holes, and everything else, you can go to youtube.com/scishowspace to subscribe.
宇宙里不断发生着各种各样的事情，如果您想了解与行星、月球、黑洞等有关的最新消息，不妨订阅youtube.com/scishowspace to subscribe。
