了解宇宙是如何运行的（2010）

How the Universe Works S09E05

Part 3 March 16, 2022, 8:55 a.m.

the universe,
to reach that point.
这是大多数中等大小恒星的黑暗命运
This is the dark destiny
of most midsized stars,
包括我们的太阳
including our sun.
这种漫长而缓慢的死亡可能会让白矮星看起来很普通
This long, slow death may make
white dwarfs seem ordinary,
但这些小恒星可以回答
but these tiny stars
could answer
关于我们宇宙的一些重大问题
some big questions
about our universe.
庞泽:它们可能很小也可能很暗
PONTZEN: They might be small,
and they might be dim,
但它们对我们理解物理学至关重要
but they are essential for
our understanding of physics.
关于白矮星新的研究
New research into
white dwarfs may answer
可能会回答一个最大的问题……
one of the biggest questions
of all...
生命能在恒星死亡后继续存在吗？
Can life survive the death
of its star?
在过去，我们低估了
In the past,
we've underestimated
白矮星
white dwarfs,
但现在它们在天文学家中引起了轰动
but now they're causing
a buzz among astronomers.
过去十年来的一个重大问题是
One of the big questions
over the last
一颗行星能否在白矮星周围生存？
decade is could a planet
survive around a white dwarf?
逻辑上的答案是否定的
The logical answer would be no.
在它们变成白矮星的过程中
On their way to becoming
white dwarfs,
恒星会经历一个红巨星阶段
stars evolve through
a red giant phase.
它们会变得非常巨大
They expand to become very huge.
所以我们认为这些恒星周围的
So we figured any planets around
任何行星都可能被吃掉
these stars might just
get eaten.
2019年12月，来自巨蟹座的证据
In December of 2019,
evidence from the constellation
推♥翻♥了这个想法
of Cancer turned that idea
on its head.
天文学家在距离地球约1500光年的地方
Astronomers spotted
a strange-looking white dwarf
发现了一颗长相奇特的白矮星
about 1,500 light-years
from Earth.
这颗恒星发出的细微变化的光
Subtle variations in light
from the star
揭示了一个谜……
revealed a mystery...
氧元素和硫元素的数量是之前
The elements oxygen and sulfur
in amounts never
白矮星表面上从未见过的
before seen on the surface of
a white dwarf.
我们知道白矮星的化学特征是什么
We know what the chemical
signature of a white dwarf is,
就像一加一等于二一样
and this stuck out
like a sore thumb.
正常情况下
Normally, hydrogen and helium
白矮星的外层由氢和氦组成
make up the outer layers
of a white dwarf.
氧和硫
Oxygen and sulfur
比氢和氦重
are heavier than hydrogen
and helium,
它们应该下沉了，但我们还能看到它们
and they should have sunk
down, but we still see them
所以它们肯定是最近才到那里的
there, so they must have
gotten there recently.
天文学家们利用位于智利的ESO超大望远镜
Using ESO's Very Large
Telescope in Chile,
进行了近距离观察
astronomers took a closer look.
他们发现了一颗地球大小的小白矮星
They discovered a small,
Earth-sized white dwarf
周围环绕着一个大约10倍于太阳宽度的
surrounded by a huge gas disc
roughly 10 times
巨大气体盘
the width of the sun.
圆盘里含有氢、氧和硫
The disc contained hydrogen,
oxygen, and sulfur.
希尔兹:像这样的系统以前从未见过
SHIELDS: A system like this had
never been seen before,
所以下一步就是查看这些元素的特性
and so the next step was to
look at a profile of these
并找出我们在哪里
elements and figure out where
见过类似的东西
we'd seen something similar.
令人惊奇的是，我们找到了
And the amazing thing is,
we have.
我们在太阳系的冰巨星天王星
We've seen these elements in
the deeper layers of the ice
和海王星的深层
giants of our solar system,
看到了这些元素
Uranus and Neptune.
在这个气体环中隐藏着一颗巨大的
Hidden in the gas ring
is a giant,
类似海王星的冰冻行星
Neptune-like icy planet.
它是恒星的两倍大
It's twice as large as the star,
但来自白矮星的5万度高温正在慢慢蒸发
but the fierce 50,000-degree
heat from the white dwarf is
这颗绕轨道运行的行星
slowly evaporating
this orbiting planet.
希尔兹:白矮星
SHIELDS: The white dwarf
正在用高能辐射、X射线和紫外线
is bombarding the planet with
high-energy radiation, X-rays,
轰击星球
UV rays.
它粉碎了大气层中的冰分子
It's pulverizing the ice
molecules in its atmosphere
并将它们吹向太空
and blowing them out into space,
这些冰分子就像彗星的尾巴一样
and the ice molecules are
streaming behind
在行星后面流动
the planet like
the tail of a comet.
这颗冰雪星球的质量
The icy planet loses mass at
以每秒超过50万吨♥的速度流失
a rate of over 500,000 tons
per second.
这相当于每分钟300艘航♥空♥母舰
That's the equivalent of
300 aircraft carriers
克里斯汀森:这听起来
every minute.
- CHRISTIANSEN: It sounds like
像是星球的末日
that could be curtains
for the planet.
但要记住行星很大，而恒星在冷却
But remember,
the planet is large,
希尔兹:当它冷却的时候
and the star is cooling down.
- SHIELDS: As it cools,
它会停止猛烈地轰击星球
it will stop blasting
the planet so intently,
气体流也会停止
and that stream of
gas will cease.
这颗行星最终可能只会损失
The planet will probably
end up losing
其总质量的几个百分点
only a few percent of
its total mass.
所以这颗行星应该会
So the planet should survive
继续围绕这颗白矮星运行
and continue orbiting
the white dwarf.
但仍有一个谜
But a mystery remains.
为什么当恒星膨胀成一颗红巨星时
Why didn't the closely
orbiting planet die
这颗近距离运行的行星没有死亡？
when the star swelled
to a red giant?
希尔兹:它一定是从更远的地方开始向内移♥动♥的
SHIELDS: It had to have started
farther out and moved inwards.
我们最好的猜测是，在某种宇宙游戏中
Our best guess is that other
ice giants were probably
红巨星阶段之后的某个时候
lurking somewhere
in the outer regions
某个冰巨星可能潜伏在
of the system and knocked
that planet inwards,
系统的外部区域的某个地方
towards the white dwarf,
sometime after the red giant
这个行星开始向内
phase in some kind of
cosmic pool game,
撞向白矮星
if you will.
这并不是唯一一颗有行星存在的白矮星
This isn't the only white
dwarf with evidence of planets.
在距离地球570光年的地方
About 570 light-years
from Earth,
有一颗白矮星叫做WD 1♥1♥4♥5+017
there's a white dwarf star
called WD 1♥1♥4♥5+017.
在对这颗恒星进行了5年的研究后
After studying the star
for five years,
研究人员报告说，这颗白矮星正在撕裂并吞噬
researchers report that
the white dwarf is ripping apart
一颗小型岩态行星
and eating a mini rocky planet.
克里斯汀森:当行星被撕裂时
CHRISTIANSEN: So as the planet
is being torn up,
我们看到巨大的尘埃云挡住了恒星50%的光线
we see this huge cloud of
dust blocking out 50% of