宇宙中的最后一颗恒星——红矮星解析：英语精读讲义

One day the last star will die

有一天，最后一颗恒星将会死去，

and the universe will turn dark forever. 語法

宇宙将永远陷入黑暗。

It will probably be a red dwarf,

它可能是一颗红矮星，

a tiny kind of star

一种微小的恒星，

that's also one of our best bets to find alien life 習語

这也是我们寻找外星生命的绝佳目标之一，

and might be the last home of humanity

并可能是人类最后的家园，

before the universe becomes uninhabitable.

直到宇宙变得不再适宜居住。

So what do we know about them

那么我们对它们了解多少？

and why are they our last hope?

为什么它们是我们最后的希望？

At least 70% of stars in the universe are red dwarfs.

宇宙中至少有70%的恒星是红矮星。

They are the tiniest stars out there

它们是已知最小的恒星，

with only about 7 to 50% of the mass of our sun,

质量只有我们太阳的7%到50%，

not that much bigger than our planet Jupiter,

并不比我们的木星大多少，

which is still huge though.

尽管那仍然十分巨大。

They are also very dim.

它们也非常暗淡。

It's impossible to see them with the naked eye. 短語搭配

肉眼根本无法看到它们。

You've never seen one in the night sky.

你在夜空中从未见过它们。

Even with all our technology, 語法

即使拥有最先进的技术，

we can only clearly observe red dwarfs in our neighborhood. 習語

我们也只能清晰地观察到我们附近的红矮星。

Approximately 20 of the 30 stars close to Earth are red dwarfs.

在距离地球最近的30颗恒星中，大约有20颗是红矮星。

Like all stars, red dwarfs fuse hydrogen into helium.

和所有恒星一样，红矮星将氢聚变成氦。

But while more massive stars accumulate all the fused helium in their cores,

但是，质量较大的恒星会将聚变产生的氦全部积聚在核心，

red dwarfs stay convective,

红矮星则保持对流，

meaning that the helium and hydrogen constantly mix.

这意味着氦和氢会不断混合。

So they use up their fuel incredibly slowly 短語動詞

因此，它们消耗燃料的速度慢得惊人，

before they're extinguished.

直至最终熄灭。

Red dwarfs burn so slowly that their average lifespan 語法

红矮星燃烧得如此缓慢，以至于它们的平均寿命

is between 1 and 10 trillion years.

在1万亿到10万亿年之间。

By comparison, the sun will survive for another 5 billion years. 表達脈絡

相比之下，太阳只能再存活大约50亿年。

Because the universe is only 13.75 billion years old,

因为宇宙只有137.5亿年的历史，

not a single red dwarf has reached later development stages. 語法

所以没有一颗红矮星达到了演化的后期阶段。

Every single one of the trillions that exist is still a baby. 習語

现存的数万亿颗红矮星每一颗都还是个婴儿。

Speaking of babies, 表達脈絡

说到婴儿，

the smallest star in the entire universe is also a red dwarf

全宇宙最小的恒星也是一颗红矮星，

because small red dwarfs are right on the verge of being a star at all. 短語搭配

因为质量极小的红矮星正好处于成为恒星的边缘。

Just a tiny bit less hydrogen 語法

只要氢再少那么一点点，

and they are mere brown dwarfs, 用詞

它们就只会变成褐矮星，

failed stars that cannot sustain a fusion reaction for long. 用詞

即无法长久维持聚变反应的失败恒星。

So what about aliens or a new home for humanity?

那么关于外星人或人类的新家园呢？

Since our sun will die one day,

既然我们的太阳终有一天会死去，

we'll eventually need to look for a new home.

我们最终将需要寻找一个新家园。

And where there are habitable planets, 語法

而在有宜居行星的地方，

there might also be aliens.

也可能存在外星人。

The Kepler space observatory found 文化背景

开普勒空间望远镜发现，

that at least half of all red dwarfs host rock planets 用詞

至少一半的红矮星拥有岩石行星，

between half and four times the mass of our Earth.

质量在我们地球的一半到四倍之间。

Many of them are in the habitable zone, 用詞

其中许多位于宜居带内，

the area around a star where water can be liquid.

即恒星周围能让液态水存在的区域。

But since red dwarfs burn at relatively cold temperatures,

但由于红矮星燃烧的温度相对较低，

a planet would need to be really close to be hospitable,

行星必须靠得非常近才能适宜居住，

probably as close as Mercury to our sun or even closer. 語法

也许要像水星离太阳那样近，甚至更近。

Which brings with it all kinds of problems. 表達脈絡

这就带来了各种问题。

For example, a planet this close to a star

例如，离恒星这么近的行星

would probably be tidally locked, 用詞

很可能会被潮汐锁定，

meaning the same side would always face it.

这意味着它总是以同一面朝向恒星。

This side would be incredibly hot,

这一面会酷热无比，

while the shadow side would be frozen, 語法

而阴影面则会被冰冻，

which makes it hard for life to develop. 語法

这使得生命很难在此孕育。

Although a planet with a big enough ocean

虽然，一颗拥有足够大海洋的行星

might be able to distribute the star's energy

也许能够将恒星的能量分散开来，

and create some kind of stability.

从而创造出某种稳定性。

Or the gravitational forces of the red dwarf

又或者，红矮星的引力

could squeeze the planet

可能会挤压行星，

and heat it up so much 語法

使其温度升得如此之高，

that it might lose all its water over time.

以至于它可能随着时间的推移失去所有的水。

These planets could end up like Venus, 短語動詞

这些行星最终可能会变得像金星一样，

a hot, burning hell.

成为一个酷热燃烧的地狱。

Another problem is that many red dwarfs

另一个问题是，许多红矮星

vary in their energy output. 短語搭配

它们的能量输出是不稳定的。

They can be covered in star spots

它们表面可能会布满星斑，

that can dim their emitted light

这些星斑会让它们发出的光变暗

by up to 40% for months, 語法

长达数月之久，最高可减弱40%，

which would cause oceans on planets to freeze over. 短語動詞

这会导致行星上的海洋结冰。

At other times, they can emit powerful solar flares, 講解

在另一些时候，它们能释放强大的耀斑，

sudden outbursts of energy,

即能量的突然爆发，

incredibly powerful.

威力惊人。

These red dwarfs can double their brightness in minutes,

这些红矮星能在几分钟内亮度翻倍，

which could strip away sizable portions of a planet's atmosphere 短語動詞

这可能会剥离行星相当大一部分的大气层，

and burn it,

并将其灼烧，

rendering it sterile. 語法

使其变得寸草不生。

On the other hand, 表達脈絡

另一方面，

their extremely long lifespan is a big plus. 用詞

它们极长的寿命是一个巨大的加分项。

A red dwarf with just moderate levels of activity

一颗活跃度适中的红矮星

could be an amazing place for a planet that hosts life.

可能成为孕育生命的行星的绝佳场所。

Life on Earth has existed for about 4 billion years 語法

地球上的生命已存在了大约40亿年，

and we have about a billion years left 短語搭配

我们大约还剩下10亿年的时间，

before the sun becomes so hot

之后太阳将变得异常灼热，

that complex life on Earth will become impossible.

以至于地球上无法再存在复杂的生命。

We will either die 語法

我们要么灭绝，

out or leave Earth and look for a new home.

要么离开地球去寻找一个新家园。

We could build a civilization

我们也许能建立一个文明，

for potentially trillions of years

延续可能长达数万亿年，

around a red dwarf with the right conditions.

围绕着一颗条件适宜的红矮星。

About 5% of the red dwarfs in the Milky Way

银河系中大约5%的红矮星

may host habitable,

可能拥有宜居的、

roughly Earth-sized planets.

差不多地球大小的行星。

That would be more than 4 billion in total.

总数将超过40亿颗。

But life may not even need a planet like Earth. 語法

但生命甚至可能不需要像地球一样的行星。

Candidates for life around a red dwarf

红矮星周围可能孕育生命的候选地，

may be the moons of gas giants

可能是气态巨行星的卫星，

or so-called super-Earths, 用詞

或者是所谓的“超级地球”，

really massive rocky planets.

即质量极大的岩石行星。

All in all, there are an estimated 60 billion 表達脈絡

总而言之，据估计约有600亿颗

potentially habitable planets around red dwarfs

潜在宜居的行星围绕着红矮星，

and that's in the Milky Way alone.

而且这仅仅是在银河系内。

So red dwarfs might become really important

因此，红矮星可能会变得非常重要，

for our survival in the future.

对于我们未来的生存而言。

But everything has to die at some point,

但万物终有一死，

even red dwarfs.

哪怕是红矮星。

When in trillions of years

当几万亿年后，

the life of the last red dwarf in the universe

宇宙中最后一颗红矮星的生命

is about to end, 語法

即将走向终点时，

it will not be a very spectacular event.

这不会是一个非常壮观的事件。

As its hydrogen runs out, it shrinks, 短語動詞

随着它的氢耗尽，它会收缩，

becoming a blue dwarf,

变成一颗蓝矮星，

burning out completely. 短語動詞

直至彻底燃尽。

After its fuel is spent,

燃料耗尽后，

it's transformed into a white dwarf, 短語搭配

它转变为一颗白矮星，

an object about as small as Earth,

这是一个大小跟地球差不多、

packed very densely and made of degenerate gases, 語法

极其致密、由简并气体构成的天体，

mostly of helium-4 nuclei.

主要成分是氦-4原子核。

Having no more source of energy, 語法

既然没有了能量来源，

it will cool extremely slowly over trillions of years

它将在数万亿年的时间里极其缓慢地冷却，

until it becomes its final form,

直到变成它的最终形态——

a cold black dwarf.

一颗冰冷的黑矮星。

White and black dwarfs are so fascinating

白矮星和黑矮星如此令人着迷，

that they deserve their own video.

值得专门做一期视频来讲述。

Anyway, it's going to be a long time 語法

无论如何，还要过很久很久，

before the last stars in the universe vanish.

宇宙中最后的恒星才会消失。

It's kind of uplifting to know 語氣意圖

知道这点算是让人有些欣慰：

that if humanity succeeds in venturing into space, 短語搭配

如果人类成功探索太空，

we have plenty of time

我们还有充足的时间，

before the universe turns out the lights. 習語

在宇宙熄灭所有灯光之前。

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如果你想帮助我们制作更多视频，

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