了解宇宙是如何运行的（2010）

How the Universe Works S06E03

Part 5 Dec. 22, 2021, 7:22 p.m.

我们对宇宙的理解就越好
当我们第一次开始这个探索系外行星计划时
它实际上不仅仅只是一个“狩猎”的阶段
现在我认为我们已经到了聚集的阶段
我们发现了许许多多的系外行星
最终能够让我们了解
在系外行星系统中形成这些世界的机制
望远镜不仅仅是在观察单个恒星
它们也在搜索双星系
这也是科学家们最想找到一件事
如果我们在双星系中
发现一个真正像地球一样的行星
这将是一个不可思议的发现
所以在很多方面
这将是我们在双星系中寻找行星的圣杯
但事实证明，在双星系中寻找岩石行星
But finding rocky planets in binary systems
是件非常困难的事
is proving difficult.
我们已经发现了绕双星系运行的行星
We have found planets orbiting binary star systems,
这在我们对宇宙运作方式的理解上
and that's a big leap forward in our understanding
是一个巨大的飞跃
of how the universe works.
不幸的是，这些行星都是气态巨行星
Unfortunately, those planets have all been gas giants,
它们不适合形成生命
and they're not really good for forming life.
外星文明要想在两个太阳周围生存
For alien civilizations to exist around two suns,
就需要坚实的地面
they need solid ground.
到目前为止，我们对科幻世界的探索
The hunt for the world of our Sci-Fi dreams
还没有结果
has so far been fruitless.
我们经常在思考，也许双星周围
We always have to consider that maybe rocky planets
并不存在岩石行星
around binary stars
什么原因是我们目前还不知道
just don't exist for some reason that we currently don't know.
这就意味着塔图因星球将不复存在
And that would mean there would be no Tatooine.
双星是否会使岩石行星
Could paired stars make it impossible
不可能形成？
for a rocky planet to form.
如果你是一颗试图在双星系周围形成的行星
If you're a planet trying to form around a binary system,
中间的引力总是在变化的
the gravity in the middle is always changing.
现在不是一颗恒星，而是两颗恒星
Instead of a single star, you have two stars
围绕彼此运行
orbiting each other.
这两颗新生恒星
These two infant stars
开始了引力拉锯战
start a gravitational tug-of-war.
它们之间的物质被拉向不同的方向
The material between them is pulled in different directions,
使得岩石碎片和灰尘难以粘在一起
making it harder for bits of rock and dust to stick together.
这个恒星系似乎太混乱了，无法形成岩态行星
The system seems too chaotic for rocky planets to form.
复杂的引力作用
The complex gravitational interactions
使许多潜在轨道失去稳定
at play destabilize a lot of potential orbits.
对于一个年轻的行星来说
There aren't a lot of opportunities for a young planet
想要在这个双星系统周围找到一个稳定的
that might want to form to find a stable, long-term home
持续数十亿年的长♥期♥家园的机会并不多
that lasts for billions of years around that binary system.
相对来说，被恒星驱逐或消耗
It's relatively easy to get ejected or consumed
却是比较容易的
by the stars themselves.
那么，为什么岩石行星不能生存
So, why can't rocky planets survive
而气态巨行星却可以？
when gas giants can?
任何一个好的房♥地♥产♥经纪人都会告诉你
As any good realtor will tell you, it's all about
位置、位置、位置
location, location, location.
我们认为岩石行星倾向于在恒星附近形成
We think that rocky planets tend to form close in around stars
那里温暖宜人，但在更远的地方，那里较冷
where it's nice and warm, but further out where it's colder,
就会形成气态巨行星
you have the gas giant planets forming.
所以，如果有一个双星系
So, if you have a binary star system,
它就像一个引力龙♥卷♥风♥把所有的岩石物质
it's like a gravitational tornado whipping out
都刮了出来
all of that rocky material
只剩下冰冷的物质，这些物质在更远的地方
so that you're only left with the cold stuff,
就可以形成气态巨行星
which can form gas giants further out.
如果一个双星系是一个城市
If a two-star system were a city,
那么这些气体巨星就在郊区
the gas giants are out in the suburbs.
一个远离两颗恒星♥相♥互竞争的引力的
A nice, peaceful spot away from the competing gravity
好地方
of the two stars.
也许还一星系比两星系更好
Perhaps one-star systems are better than two.
气态巨行星不适合生命存在
Gas giants aren't great for life,
这些就是我们在双星系中发现的行星
and those are the planets we're finding in these binary systems.
我们之所以在这里的原因可能就是
The very reason that we're here could be down to the fact
我们有一颗恒星而不是两颗
that we have one star rather than two.
但2017年
But in 2017,
一项距离地球约2000光年的发现
a discovery around 2,000 light years away
给了我们新的希望
gives us new hope.
所以，当我们在宇宙中发现新事物时
So, as we discover new things in the universe,
我们倾向于给它们取目录名
we tend to give them catalogue names,
这可能非常无聊
which can be very boring
也很难追踪
and very difficult to keep track of.
但SDSS 1557值得记住
But SDSS 1557 is worth remembering.
我们已经看到了一个双星系，它是一颗白矮星……
We've seen a binary system that is a white dwarf...
它是像太阳这样的恒星的核心
Which is the core of a star like the sun
当它变得非常老的时候
after it's gotten very old,
它的外层已经被吹走了……它的轨道上有一颗褐矮星
blown off its outer layers... That's orbited by a brown dwarf,
这样的一颗星体是
an object which is sort of on the border
介于行星和恒星之间
between a planet and a star.
SDSS 1557系统最令人兴奋的地方是
What's most exciting about the SDSS 1557 system
我们发现了岩石碎片
is that we've found rocky debris.
我们看到了基本的物质
We see the basic materials,
构成行星的基本成分
the basic ingredients are there for forming planets.
这是一个非常令人兴奋的发现
This is a really exciting discovery
因为我们看到了小行星和岩石的残余
because we've seen the remnants of asteroids
围绕着这个古老的双星系运行
and rocks orbiting about this ancient binary system,
在此之前我们认为，这个系统不可能
systems that we thought could've never had surviving
有岩石类型的物质存在
rocky-type things around it before.
这个双星系已经有数十亿年的历史了
This binary system is billions of years old,
在这段时间里
and through all that time,
岩石物质并没有被彻底清除
the rocky material hasn't been wiped out.
它活了下来
It has survived.
这是一个巨大的踏脚石，寻找我们的有两个太阳的
This is a huge stepping stone to finding our rocky planet
岩石行星
with two suns.
该系统提供的证据表明，在双星系附近
The system provides evidence there's rocky material
有岩石物质存在
close in around a binary star system,
因此这是一个标志，表明岩石行星
so it's a signpost that rocky planet formation
可以在双星系周围形成
can occur around binary star systems.
可能性是会更大，还是只是有可能
The odds might be longer, but it's still possible.
这个恒星系里还会有行星吗？
Could there even still be a planet in this system?
在SDS 1557附近可能仍然存在行星物体
There may still be planetary objects around SDS 1557.
我们只是还没看到它们，但它们可能还在那里
We just haven't seen them yet, but they may still be there.
搜寻工作仍在继续
The search is still on.
一颗围绕两颗恒星运行的岩石行星可能真的存在
A rocky planet orbiting two stars could really exist.
所以，对于那些希望看到塔图因的人
So, for those of us hoping for that Tatooine out there,
那个有双重日落的行星
that planet with the double sunset,
这些碎片场实际上给了我们希望
these debris fields actually give us hope.
也许至少，这种条件还是有可能
Maybe the conditions, at least, are right for the formation
在双星周围形成岩态行星的
of rocky planets around binary stars.
我想它就在那里
I think it's out there.
我认为找到它更多的是何时而非是否的问题
I think finding it is more a question of when than if.
作为一名天文学家，这是一个在边缘地方发现生命的
As an astronomer, this is a fantastic time to be alive
美妙时刻
at the cusp of discovery.
作为一个科幻迷，这是一个美好的时代
As a science fiction fan, this is a fantastic time to be alive
因为我小时候看到的东西正在变成现实
because the stuff I read as a kid is coming true.
但也许最大的科学幻想
But perhaps the biggest Sci-Fi fantasy
更接近现实
is much closer to home,
因为最新研究发现了一些令人震惊的东西……
because new research is suggesting something stunning...
我们自己的太阳可能有一个双胞胎
Our own sun could have a twin.
2017年的一项新的研究对我们对太阳的理解提出了质疑
A new study in 2017 throws into question
our understanding of the sun.
这是天文学家第一次
For the first time now, astronomers are able to peer
能够窥视形成恒星的星云内部
inside the clouds that form stars,
令人惊奇的是，有证据表明每一颗类日恒星
and the amazing thing is that the evidence is suggesting
都是作为双星的一部分形成的
that every single sun-like star forms as part of a binary pair.
科学家们研究了英仙座分子云
The scientists study the Perseus molecular cloud,
这是一个距离我们750光年的恒星托儿所
a stellar nursery around 750 light years from us,
里面充满了像太阳一样的恒星
packed with stars just like our sun.
它们中的许多都处于宽阔的双星系中
Many of them are in wide binary systems,
在围绕彼此的巨大轨道上运行
traveling in huge orbits around each other
跨度长达数百光年或更久
that span centuries or more.
所有这些双星都是婴儿
And all of these binaries are babies,
不到50万年
less than 500,000 years old.
解释这些年轻恒星系是如何形成的
The only way to explain these young systems