了解宇宙是如何运行的（2010）

How the Universe Works S09E05

Part 1 March 16, 2022, 8:55 a.m.

白矮星
White dwarfs,
一种小恒星，但其能量巨大
small stars that pack
a big punch.
当白矮星刚被发现时
When white dwarfs
were first discovered,
天文学家的反应是不，不，不，不
astronomers' reaction
was no, no, no, no,
不，不，不，那不可能是真的
no, no, no, that can't be real.
布洛克:这些东西里面的情况
BULLOCK: What's going on
inside these things
只能用非常奇怪来形容
can only be described
as seriously weird.
白矮星是像太阳一样的恒星
They're the cooling
corpses of stars
冷却的尸体
like our sun,
但新的研究证明
but new research proves
white dwarfs are
白矮星是我们宇宙的驱动力之一
one of the driving forces of
our universe.
普莱特:它们吞噬行星，发出高能量的光
PLAIT: They eat planets, they
flare out in high-energy light.
它们真的会爆♥炸♥
They can really explode.
它们可以告诉我们
And they can tell us literally
宇宙的本质
about the nature of
the universe itself.
白矮星科学的核心
And there's a dirty secret at
有一个肮脏的秘密
the heart of
white dwarf science.
霍普金斯:我们看到恒星死亡爆♥炸♥
HOPKINS:
We see dead stars exploding,
但我们仍然不明白它们为什么会这样
and we still don't understand
why they're doing it.
科学家们最终发现了这些小恒星
Have scientists finally
discovered how these small
是如何成为如此巨大的星系参与者的吗？
stars could be such massive
galactic players?
[爆♥炸♥]
[explosion blasts]
宇宙是如何运行的
第九季第5集白矮星的诅咒
2018年12月
December 2018.
天文学家发现了奇怪耀斑
Astronomers spot
strange flares coming from
它来自距离地球2.5亿光年的
a galaxy 250 million
light-years from Earth,
星系GSN 069
GSN 069.
我们知道GSN 069的中心有一个超大质量黑洞
We know that GSN 069 has
a supermassive black hole in
它的质量大约是
its center, equal to about
太阳质量的50万倍
half a million
times the mass of the sun.
这是一个巨大的黑洞
That's a big black hole,
它以非常非常稳定的速度
and it blasts out X-rays in
发射着X射线，每9小时
a very, very steady pace,
发射一次为什么？
every nine hours. Why?
耀斑的能量如此之大，规律如此之多
The flares are
so energetic and regular,
超大质量的黑洞
the supermassive black hole
must be eating the mass of
必定每天三次吞噬水星的质量
the planet Mercury
three times a day.
最大的问题是，是什么哺育了黑洞
The big question is what's
feeding this black hole
如此丰盛的晚餐？
such a huge dinner?
2020年3月，科学家们找到了答案
In March 2020,
scientists found the answer.
一颗不幸的恒星在其生命的尽头
An unlucky star at the end of
its life
徘徊在黑洞的死亡地带
had wandered into the death
zone of the black hole.
奥卢塞伊:一颗恒星离超大质量黑洞太近
OLUSEYI: A star getting
too close to a supermassive
就像一个光滑的甜甜圈
black hole is like
a glazed doughnut
离我太近一样
getting too close to me.
那东西撑不下去了
That thing just is not
gonna make it.
霍普金斯:恒星离黑洞太近
HOPKINS: Stars to get too close
to a black hole
就会被撕裂
get torn apart.
它们受到了黑洞的攻击
They sort of get attacked
by the black hole,
其中一些物质
and some of that material
is also getting launched
以非常强大的风和喷射流
off in very powerful winds
and jets and streams
被发射出去
getting out.
不知为何，这颗恒星在与超大质量黑洞的
Somehow, the star
survives its close
近距离接触中幸存了下来
encounter with
the supermassive black hole.
进一步的研究表明它是一颗小型致密恒星
Further investigation reveals
it's a small, compact star,
一颗白矮星
a white dwarf.
那么是什么让这颗小恒星坚不可摧呢？
So what makes this tiny star
almost indestructible?
答案在于它是如何形成的
The answer lies in how
it's formed.
如果我们观察一颗恒星的生命周期，我们就能得到线索
We get a clue if we look at
the life cycle of a star.
它将氢燃烧成氦，这导致核聚变
It's burning hydrogen into
helium, that's causing nuclear
从而使恒星保持稳定
fusion, and that causes a star
to stay stable.
在核聚变产生的辐射压力向外推
There's this delicate balance
between radiation pressure
和引力压力向内拉之间
from that nuclear fusion pushing
out and gravitational pressure
存在着微妙的平衡
pulling in.
但当像我们的太阳这样的恒星接近生命末期时
But when stars like our sun
near the end of their life,
它们会耗尽氢燃料
they run out of hydrogen fuel.
这颗类太阳的恒星会产生越来越多的氦
The sun-like star makes
more and more helium,
氦在其中心聚集
which builds up in its center.
逐渐地，恒星外层的
Gradually, the immense weight of
巨大重量压碎了氦核
the star's outer layers crushes
the helium core.
奥卢塞伊:随着核心年龄的增长，它变得越来越小
OLUSEYI: As the core ages,
it gets smaller and hotter,
越来越热，这就增加了核反应的速度
which increases the rate of
nuclear reactions.
这些核聚变反应产生了更多的能量
These nuclear fusion
reactions produce more energy,
将外层或包膜向外推
which pushes the outer layer,
or envelope, outwards.
因为有更多的能量通过外层
Because there's more energy
flowing through the envelope,
外层就会膨胀
the envelope swells up.
这颗恒星膨胀到原来大小的100倍左右
The star expands to around
100 times its original size.
黄色的恒星变成了红巨星
The yellow star
becomes a red giant.
最终，红巨星脱离了它们的外层
Eventually, red giants shed
their outer layers,
形成了令人惊叹的气体壳，称为行星状星云
forming stunning gas shells
called planetary nebulas.
行星状星云是太空中最美丽的天体
Planetary nebulae are the most
beautiful objects in space.
他们都很壮观
They're all spectacular.
一颗恒星在这些行星状星云中结束其生命后
A star that ends its life in
one of these planetary nebulas
会在中心留下一颗白矮星
leaves behind a white dwarf
at the center,
这颗白矮星本质上是一颗煤渣
and this white dwarf is
essentially a cinder,
一颗恒星的煤渣
a stellar cinder.
它是核聚变后的产物
It's what's left after
nuclear fusion
对于那颗特定的恒星来说不再可能发生核聚变
is no longer possible for that
particular star.
剩下的，是一颗发光的白矮星
All that remains,
a glowing white dwarf,
这颗死亡恒星的剩余核心
the leftover core
of the dead star.
但在GSN 069星系中
But in galaxy GSN 069,
超大质量黑洞加速了这一过程
the supermassive black hole
turbocharged the process.
它在几天内就剥离了
It stripped off the outer
layers of the red giant
红巨星的外层
in a matter of days.
霍普金斯:黑洞几乎吃掉了
HOPKINS: The black hole
has almost eaten
恒星所有多汁的部分，所有容易得到的部分
all the juicy parts,
all the easy-to-get-at parts
只留下骨头