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人类迄今为止发现的最古老行星

The Oldest Planet Ever Discovered

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[♪ INTRO]
2003年 天文学家发现了一颗太阳系外行星 并命名为PSR 1620-26 b
In 2003, astronomers discovered anexoplanet named PSR 1620-26 b.
这不是一个梦幻的名字
It doesn’t have a fancy name,
听起来就像另外一个气态巨行星而已
and it’s likely just another gas giant,
此时 它的质量大约是木星的两倍
this time, at about two timesthe mass of Jupiter.
它甚至可能像其它外行星一样形成
It probably even formed likeall other exoplanets out there.
科学家们认为 这颗行星只是很普通的一颗
But for scientists, this planetis anything but normal.
甚至这个发现过了15年 研究者们相信
Even fifteen years after its discovery,researchers believe it’s still the
宇宙中仍然存在我们尚未发现的更古老的行星
oldest confirmed planet we’ve ever found.
证据表明 它已经存在127亿年了
Evidence suggests that it’s 12.7 billion years old,
几乎只比宇宙年轻10亿年
barely a billion years youngerthan the universe itself.
它一定能让我们更了解行星的形成
And that had a lot to teach usabout planetary formation.
尽管这颗行星直到2000年才被发现
Although this planet wasn’tdiscovered until the 2000s, its story,
但是在人类历史上 它的故事真正开始于20世纪80年代
at least in human history,really started in the 1980s.
1988年 研究人员开始研究
In 1988, researchers began studying an object
叫梅西耶4星云或M4的星云
in a neighborhood called Messier 4, or M4.
它是一个球状星团
It’s a globular cluster,
一个非常稠密的恒星星团 距离地球约5500光年
a very dense group of stars, about 5500 light-years away.
M4星团由超过100000个恒星形成 但这次
M4 has more than 100,000 stars,but this time,
科学家们研究了一个叫PSR 1620-26的脉冲星
scientists were investigatinga pulsar called PSR 1620-26.
脉冲星是超新星爆炸的残余
Pulsars are the remnants of explosive supernovas.
它们发射出辐射光线 并像超级快的灯塔一样飞速旋转
They emit beams of radiation and spin really quickly, like super fast lighthouses.
当辐射光线拂过地球时
And as that beam sweeps across Earth,
我们可以看到恒星有规律的闪烁
we see the star flash at extremely regular intervals.
这就是脉冲星名字的由来
That’s how the pulsars got their name. Except,
另外 脉冲星的闪烁并不怎么规律
the timing of this pulsar’s flasheswasn’t quite so regular.
它们还稍稍偏离一点轨道
They were just a little bit off,
这意味着有别的天体在绕着它转
and that suggested there was something orbiting the star,
其引力把脉冲星往这边拉了一点
its gravity tugging the pulsar a little this
这就影响了观测信号
way and that and affecting those predictable signals.
所以天文学家们需要克服这个问题
So astronomers got to work.
经过多年的观测和大量的数学计算
And after multiple years ofobservation and a lot of math,
他们最终可以确定
they were eventually able to identify not one,
不是一个而是两个恒星在绕着这个脉冲星转
but two objects around the pulsar.
第一个是白矮星
The first was a white dwarf,
像太阳一样由中等大小的恒星形成的
which formed out of a mid-sized star like the Sun.
估计M4星团中含有超过40000个白矮星
It’s estimated that M4 contains more than 40,000 white dwarfs,
这并没有什么不寻常的
so this wasn’t that unusual.
尽管 另一颗天体是一颗行星
The second object, though, was a planet.
这就更出乎意料了
And that was a lot more unexpected. See,
在2003年
by 2003,
天文学家已经开始在各处发现了系外行星
astronomers had started finding exoplanets all over the place,
甚至发现了一些行星绕着其它脉冲星旋转
and we’d even found a feworbiting another pulsar.
但是还没有人在球状星团中
But no one had ever found a planet
发现行星
in a globular cluster,
并且很多科学家甚至并不确定是否有这个可能
and many scientists weren’tsure it was even possible.
像M4这样引力相互作用的地方可以把小行星撕裂
Gravitational interactions in placeslike M4 can rip baby planets apart,
伴之还有许多物质在绕着它转 产生更多的影响
and with tons of stuff flying around, there are lots of major impacts.
这并不是行星形成的好地方
It’s just not a great place for planets to form, except,
但是这个行星还是存活下来了
this one managed to survive. Today,
直到今天 它还是唯一一颗
it’s actually still the
我们在球状星云附近发现的行星
only known planet we’ve seen in a globular cluster. Somehow,
尽管如此 这还不是
though, that still wasn ’t
在M4星团中发现行星最特别的部分
the strangest thing about finding a planet in M4.
更奇怪的是 这块星云年龄非常大
What was even weirder is that this neighborhood is really old,
大约127亿岁了
about 12.7 billion years old.
根据我们掌握的信息
According to what we know about cluster formation,
这意味着这个群体附近的恒星也同样古老
that means the stars withinthis group are equally ancient.
延伸开来 这些恒星附近的行星也会如此古老
And by extension, so are any planets aroundthem.
即使是现在 我们仍然在探索行星的形成
Even now, we’re still figuring out exactly how planets form,
目前普遍认为
but the general consensus
它们由年轻恒星的
says that they form out of the disk
运行轨道的磁场中的物质形成
of matter that orbits a young star,
聚在一起的这些物质越滚越大形成恒星
as the matter starts glomming togetherand kind of snowballing.
这被称为核心连生模型
This is called the core accretion model.
这个过程应该发生在
This process is supposed to happen soon
恒星形成后不久
after a star is born,
所以行星和它们的宿主恒星一样有相同的年龄
so planets and their host starshave about the same age.
所以M4星团中的大部分恒星
So since most of the stars
差不多都130亿岁了
in M4 are nearly 13 billion years old,
照此推算 PSR 1620-26 b也有130亿岁了
it follows that this pulsar planet is, too.
它很可能是迄今为止人类发现的最古老的行星
And that makes it likely theoldest planet ever discovered.
这不仅仅是另一个记录而已
That’s more than just another record, though.
它也让我们更加认识到了早期的宇宙
It also has a lot to teach us about the early universe. See,
看 核心连生模型就是一个例子
the thing about thecore accretion model is that,
如果你想通过滚雪球的方式做一个行星模型
if you’re going to form a planetby snowballing stuff,
你还需要很多不同的重金属元素
you need to have a lotof heavy, diverse elements.
即使是气态巨星也不仅仅只有氢气和氦气
Even gas giants are more thanyour basic hydrogen and helium.
但这些并不是自宇宙大爆炸后就
But it’s not like those heavy elements have existed
存在的元素
since the Big Bang. Instead,
而是经过了数百万年才形成的
it took millions of yearsfor them to form.
这些元素只会伴随着恒星的形成而形成
They only began to exist as stars were born,
一开始较轻的元素融合在一起
fused lighter elements together,
然后在死后释放较重的元素
and then spit out theheavier products when they died.
这就是为什么PSR 1620-26 b脉冲星是一个突破性的发现
And that’s why finding this pulsar planet was such a big deal.
这可是第一个物理证据表明
It was the first piece of physical evidence announcing that,
大约130亿年前
nearly 13 billion years ago,
就已经有足够多的重金属元素开始形成行星了
there were enough heavy elements to startforming planets after all.
它证实了研究者们思考了很多年的问题
It confirmed something researchershad been thinking about for years,
也暗示着很可能还有其它古老的
and it also hinted that there could be other ancient worlds
领域
out there, too.
自从2003年 天文学家发现了更多古老的行星
Since 2003, astronomershave found more old planets,
但是没有一个可以推翻PSR 1620-26 b的记录
but none of them havebeen able to topple this record.
就我们目前所知 它确实应该是冠军
But from what we now know,they should be out there.
所以我们继续看看吧
So we’ll just have to keep looking.
感谢收看本集《科学秀空间》
Thanks for watching this episodeof SciShow Space!
在这里 我们乐于搜集研究中最奇怪
We love scouring the research for the weirdest,
最惊奇 最令人敬畏的事情
most surprising, and most awe-inspiring stuff
但是我们
out there, but we’d love
也想知道你想获悉什么
to hear what you want to learn about, too.
如果你对于下一期的《科学秀空间》有什么建议
If you have a suggestion forfuture SciShow Space videos,
请去评论区写下来
go ahead and leave them in the comments,
我们会看到的
and we’ll look into it.
和往常一样 你可以在油管网 《科学秀空间》和订阅频道
And as always, you can keep upwith the latest videos
观看最新的视频
by going to youtube.com/scishowspaceand subscribing.
[音乐]
[♪ OUTRO]

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视频概述

宇宙是一个非常神秘莫测的地方,其中有许许多多的天体,我们渴望去探索他它们,认识它们。视频介绍了人类迄今为止发现的一颗最古老的行星,通过它我们更加认识了宇宙。

听录译者

收集自网络

翻译译者

Scarlett

审核员

审核员 V

视频来源

https://www.youtube.com/watch?v=K3OZIH2GAPw

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