Garik Israelian: What's inside a star?

翻译人员: Chunlei Chang 校对人员: dahong zhang

I have a very difficult task.

我有一个非常困难的任务.

I'm a spectroscopist.

我是一个光谱学家.

I have to talk about astronomy without showing you

我需要向你们解释什么是天文学

any single image of nebulae or galaxies, etc.

但不能用任何星云或星系之类的图片。

because my job is spectroscopy.

因为我是从事光谱学的。

I never deal with images.

我从不与图片打交道。

But I'll try to convince you

但我会说服你

that spectroscopy is actually something which can

光谱学这个学科其实可以

change this world.

改变这个世界.

Spectroscopy can probably answer the question,

光谱学很可能解答如下问题，

"Is there anybody out there?"

"在地球之外有任何生命存在吗?"

Are we alone? SETI.

人类是孤独的吗? SETI(搜寻地外文明)

It's not very fun to do spectroscopy.

从事光谱学并不是很好玩.

One of my colleagues in Bulgaria,

我有一个在保加利亚的同事,

Nevena Markova, spent about 20 years

Neviana Markova, 花了近20年的时间

studying these profiles.

来研究这些资料。

And she published 42 articles

并且她发表了42篇文章

just dedicated to the subject.

仅仅致力于这个题目。

Can you imagine? Day and night, thinking,

你能想像吗?没日没夜地思考、

observing, the same star for 20 years

花20年时间去观察去研究同一颗恒星

is incredible.

太不可思议了。

But we are crazy. We do these things.

但我们疯了。我们做这些事。

(Laughter)

(笑声)

And I'm not that far.

我没有那么疯狂.

I spent about eight months working on these profiles.

我花了大概八个月的时间去研究这些资料.

Because I've noticed

我注意到

a very small symmetry

一些小的对称性

in the profile of one of the planet host stars.

存在于一个行星的主恒星的资料里。

And I thought, well maybe there is Lithium-6 in this star,

我认为,可能这颗恒星存在着锂6(Lithium-6)这种物质,

which is an indication that this star

这表明了这颗恒星

has swallowed a planet.

曾经吞没过一颗行星.

Because apparently you can't have this fragile isotope

因为很明显,这种不稳定的锂6同位素不可能

of Lithium-6 in the atmospheres of sun-like stars.

存在于那种类太阳的恒星的大气层中.

But you have it in planets and asteroids.

但这种同位素存在于行星或者小行星中.

So if you engulf planet or large number of asteroids,

所以,如果吞没了行星或者大数量的小行星.

you will have this Lithium-6 isotope

就会有锂6同位素

in the spectrum of the star.

出现在这颗星的光谱里。

So I invested more than eight months

所以我投入了八个多月的时间

just studying the profile of this star.

全部用于研究这颗星关于锂的数据.

And actually it's amazing,

事实上这件事是相当神奇.

because I got phone calls from many reporters asking,

因为我接到一些记者的电话采访,

"Have you actually seen the planet going into a star?"

"你有没有亲眼看到这颗行星撞击到一颗恒星里?"

Because they thought that if you are having a telescope,

因为他们认为如果你有一个天文望远镜,

you are an astronomer so what you are doing

你是一个天文学家,那么你要做的

is actually looking in a telescope.

就是用天文望远镜去实际观察.

And you might have seen the planet going into a star.

所以你可能看到过行星撞击进入颗恒星.

And I was saying, "No, excuse me.

可我只能说, "不,抱歉,

What I see is this one."

其实我所看到的是这个"

(Laughter)

(笑声)

It's just incredible. Because nobody understood really.

这确实令人难以置信. 因为没人真正理解.

I bet that there were very few people

我打赌只有非常少的一部分人

who really understood what I'm talking about.

真正理解我现在讲的东西.

Because this is the indication that the planet went into the star.

因为这是一颗行星撞击进入恒星的迹象.

It's amazing.

太神奇了.

The power of spectroscopy

光谱学的力量

was actually realized

其实曾经在1973年

by Pink Floyd already in 1973.

被Pink Floyd (歌手)提及过.

(Laughter)

(笑声)

Because they actually said that

因为他们曾经说过

you can get any color you like

任何一种你喜欢的颜色

in a spectrum.

都可以从光谱中获得.

And all you need is time and money

但你所需要的是时间和钱

to make your spectrograph.

来制作你的光谱图像.

This is the number one high resolution,

这是高清解析度之王,

most precise spectrograph on this planet, called HARPS,

这个星球上最精确的光谱仪,叫HARPS.

which is actually used to detect

实际上是用来探测

extrasolar planets and sound waves

外太阳系行星

in the atmospheres of stars.

和恒星大气层中的声波.

How we get spectra?

我们如何得到光谱呢?

I'm sure most of you know from school physics

我相信你们大部分人都从高中物理中了解过,

that it's basically splitting a white light

基本上就是从一束白光折射分解成

into colors.

不同的颜色.

And if you have a liquid hot mass,

如果你有一个热液体物质，

it will produce something which we call a continuous spectrum.

将会产生我们所谓的连续谱。

A hot gas is producing emission lines only,

热气体会仅产生出发射谱线,

no continuum.

并不连续。

And if you place a cool gas in front of a

如果你将一些冷气体

hot source,

放在一个热源前面,

you will see certain patterns

你将会看到特定的图案

which we call absorption lines.

我们称之为吸收谱线.

Which is used actually to identify chemical elements

实际上它用于鉴定化学元素

in a cool matter,

在冷却的物质中,

which is absorbing exactly at those frequencies.

因为这种化学元素完全吸收掉这些频段.

Now, what we can do with the spectra?

现在,我们可以研究光谱,

We can actually study line-of-sight velocities

我们实际上研究的是宇宙天体的

of cosmic objects.

视向速度。

And we can also study chemical composition

并且我们还可以研究化学成分

and physical parameters of stars,

和物理参数. 这些来自恒星以及

galaxies, nebulae.

星系和星云.

A star is the most simple object.

恒星是一个最简单的对象.

In the core, we have thermonuclear reactions going on,

在内核我们有持续的热核反应

creating chemical elements.

创造着化学元素.

And we have a cool atmosphere.

并且我们有低温的气体.

It's cool for me.

对我来说是低温,

Cool in my terms is three or four or five thousand degrees.

低温在我的术语里意味着三千,或者四五千度。

My colleagues in infra-red astronomy

我有些红外线天文学的同事们

call minus 200 Kelvin is cool for them.

把所有零下200K 的温度叫低温.

But you know, everything is relative.

但你知道,任何事物都是相对的.

So for me 5,000 degrees is pretty cool.

所以对我来说5000度是相当的低温呐.

(Laughter)

(笑声)

This is the spectrum of the Sun --

这是太阳的光谱.

24,000 spectral lines,

两万四千条光谱线,

and about 15 percent of these lines is not yet identified.

大约有15%的线条还没有被识别出来.

It is amazing. So we are in the 21st century,

这是惊人的. 那么我们处在21世纪，

and we still cannot properly understand

我们依然没有完全的理解

the spectrum of the sun.

太阳的光谱.

Sometimes we have to deal with

有些时候我们不得不

just one tiny, weak spectral line

跟一些细小的,微弱的光谱线条打交道.

to measure the composition of that chemical element in the atmosphere.

来测量大气的化学元素构成.

For instance, you see the spectral line of the gold

举个例子,你看这些金元素的光谱线

is the only spectral line in the spectrum of the Sun.

是太阳光谱中仅有的光谱线

And we use this weak feature

我们用这个微弱的特征

to measure the composition

来测量

of gold in the atmosphere of the Sun.

太阳大气中金元素的构成.

And now this is a work in progress.

现在,这项工作取得了很大的进展.

We have been dealing with a similarly very weak feature,

我们已经论述了一个相似的,也是非常微弱的特征,

which belongs to osmium.

是锇元素.

It's a heavy element produced in thermonuclear

这种重元素产生于

explosions of supernovae.

超新星的热核爆炸.

It's the only place where you can produce, actually, osmium.

实际上这是唯一能产生锇元素的地方.

Just comparing the composition of osmium

将锇元素的构成

in one of the planet host stars,

与这颗行星所在的主恒星相比,

we want to understand why there is so much

我们试图理解那里为什么存在如此多的

of this element.

这种元素.

Perhaps we even think that maybe

我们甚至想过,

supernova explosions trigger formations of planets and stars.

也许超新星爆炸触发了行星和恒星的形成.

It can be an indication.

这可以算一个迹象.

The other day, my colleague from Berkeley,

有天伯克利(Berkeley)的一个同事,

Gibor Basri, emailed me

Gibor Basri,发给我一个电子邮件

a very interesting spectrum,

一个非常有趣的光谱,

asking me, "Can you have a look at this?"

问我,"看看这是什么吗?"

And I couldn't sleep, next two weeks,

接下来的两周,我就睡不着觉了.

when I saw the huge amount of oxygen

我看到了大量的氧

and other elements in the spectrum of the stars.

和其它元素排列在这颗恒星的光谱中.

I knew that there is nothing like that observed in the galaxy.

我知道从银河系中没有这样的光谱.

It was incredible. The only conclusion we could make from this

难以置信! 从这个清晰的证据只能得出

is clear evidence that there was a supernova explosion

这个系统中曾经发生过一次超新星爆炸

in this system, which polluted the atmosphere

污染了这颗恒星的

of this star.

大气层

And later a black hole was formed

后来,一个黑洞

in a binary system,

在这个两元体系中形成了.

which is still there with a mass of about

现在仍然在那里,集中了大约

five solar masses.

五个太阳质量.

This was considered as first evidence that actually black holes

这被认为是第一个证明黑洞的形成

come from supernovae explosions.

是来自超新星热核爆炸.

My colleagues, comparing composition of chemical elements

我的同事们,将不同星系的化学元素的构成

in different galactic stars,

进行了对比

actually discovered alien stars in our galaxy.

便在银河系中发现了许多陌生恒星。

It's amazing that you can go so far

这太神奇了,你能了解这么多

simply studying the chemical composition of stars.

仅仅靠分析这些星球的化学元素的构成.

They actually said that one of the stars you see in the spectra

他们实际上说过,你看到这些光谱中的恒星之一

is an alien. It comes from a different galaxy.

来自于另外一个星系。

There is interaction of galaxies. We know this.

不同星际之间存在着相互作用. 我们了解这一点.

And sometimes they just capture stars.

有时他们也会捕获其它恒星.

You've heard about solar flares.

你曾经听说过太阳耀斑.

We were very surprised to discover

我们曾非常惊讶的发现

a super flare,

一个超级耀斑,

a flare which is thousands of millions of times

这个耀斑的能量比我们看到太阳的耀斑

more powerful than those we see in the Sun.

要强烈上百万倍.

In one of the binary stars in our galaxy

在银河系中

called FH Leo,

有一个叫FH Leo的双星体系,

we discovered the super flare.

我们发现过一次超级耀斑.

And later we went to study the spectral stars

后来我们去研究它的光谱

to see is there anything strange with these objects.

去理解这些对象之间有没有任何诡异的联系.

And we found that everything is normal.

然后我们发现,所有事情都很正常.

These stars are normal like the Sun. Age, everything was normal.

这些恒星像太阳一样普通. 年龄, 所有东西都是正常的.

So this is a mystery.

所以这是一个谜.

It's one of the mysteries we still have, super flares.

我们仍然未解的一个谜, 超级耀斑.

And there are six or seven similar cases

并且还有六到七个相同的案例

reported in the literature.

在文献中记载着.

Now to go ahead with this,

现在, 开始讲这个前

we really need to understand chemical evolution of the universe.

我们需要去理解宇宙化学的演变.

It's very complicated. I don't really want you to

这超级复杂. 我当然不并是真的要你去理解

try to understand what is here.

表上的这些东西.

(Laughter)

(笑声)

But it's to show you how complicated is the whole story

但这是为了告诉你,要多复杂的一个过程

of the production of chemical elements.

才能产生出这些化学元素.

You have two channels --

你有两种方法--

the massive stars and low-mass stars --

大质量恒星和低质量恒星 --

producing and recycling matter and chemical elements in the universe.

产生并回收宇宙中的物质和化学元素.

And doing this for 14 billion years,

并且已经做了140亿年,

we end up with this picture,

我们用这张图做结尾.

which is a very important graph,

这是一个很重要的图片,

showing relative abundances of chemical elements

展示出丰富的化学元素

in sun-like stars

存在于类太阳的恒星中

and in the interstellar medium.

和星际介质中.

So which means that it's really impossible

这就意味着, 你不可能找到一个物体

to find an object where you find about 10 times more sulfur than silicon,

里面的硫元素比硅元素的10倍还多,

five times more calcium than oxygen. It's just impossible.

钙比氧元素的5倍还多. 这就是不可能的.

And if you find one, I will say that

如果你真找到了,我会说

this is something related to SETI,

这跟搜寻地外文明(SETI)有关.

because naturally you can't do it.

但自然产生的,你找不到.

Doppler Effect is something very important

多普勒效应是非常重要的

from fundamental physics.

来自于基础物理.

And this is related to the change of the frequency

这是关于移动源的频率的变化.

of a moving source.

这是关于移动源的频率的变化.

The Doppler Effect is used to discover extrasolar planets.

多普勒效曾用于发现太阳系外行星.

The precision which we need

我们需要的精确数据

to discover a Jupiter-like planet

可以帮我们发现类木星的行星

around a sun-like star

围绕着类太阳的恒星

is something like 28.4 meters per second.

即是以每秒钟28.4米的速度公转.

And we need nine centimeters per second

并且我们需要每秒9厘米的速度

to detect an Earth-like planet.

去探测一个类地球的行星.

This can be done with the future spectrographs.

未来的光谱学可以完成这种任务.

I, myself, I'm actually involved in the team

事实上, 我自己参加了这个团队

which is developing a CODEX,

这个团队正在开发一种规则，

high resolution, future generation spectrograph

高解析度,下一代的光谱分析机

for the 42 meter E-ELT telescope.

42米长的E-ELT望远镜.

And this is going to be an instrument

这个仪器将用于

to detect Earth-like planets

探测围绕类太阳恒星的

around sun-like stars.

类地行星.

It is an amazing tool called astroseismology

这个很棒的工具叫天文地震仪

where we can detect sound waves

可以用来探测

in the atmospheres of stars.

来自于恒星的大气层的声波.

This is the sound of an Alpha Cen.

这是半人马座阿尔法星的声音.

We can detect sound waves

我们可以探测到

in the atmospheres of sun-like stars.

来自于类太阳恒星的大气层的声波.

Those waves have frequencies

这些有频率的声波

in infrasound domain, the sound actually nobody knows, domain.

在一个固定的声域,这种声音实际上没人听的懂.

Coming back to the most important question,

回归到我们最重要的问题,

"Is there anybody out there?"

"在地球之外有任何生命存在吗?"

This is closely related

这其实与行星的构造运动

to tectonic and volcanic activity of planets.

和火山运动密切相关.

Connection between life

生命

and radioactive nuclei

和放射性原子核之间的联系

is straightforward.

很简单直观.

No life without tectonic activity,

没有构造活动、火山活动

without volcanic activity.

就没有生命.

And we know very well that geothermal energy

并且我们知道地热能量

is mostly produced by decay of uranium, thorium, and potassium.

是铀,钍和钾元素进行衰减产生的.

How to measure, if we have planets

怎么去测量,如果有某些行星

where the amount of those elements is small,

这些元素含量非常低,

so those planets are tectonically dead,

这些行星基本上是构造性死亡,

there cannot be life.

不可能有生命存在.

If there is too much uranium or potassium or thorium,

如果那里有太多的铀,钍或者钾元素存在,

probably, again, there would be no life.

大概,同样,那里也不会有生命存在.

Because can you imagine everything boiling?

因为你可以想像所有东西都沸腾吗?

It's too much energy on a planet.

那是因为有太多能量在行星上.

Now, we have been measuring abundance

现在我们可以通过

of thorium in one of the stars with extrasolar planets.

从其它恒星和太阳系外行星测量各种元素或钍元素.

It's exactly the same game. A very tiny feature.

这些规则是一样的. 很小的一个特点。

We are actually trying to measure this profile

我们实际上正在衡量这些资料.

and to detect thorium.

并且在探测钍.

It's very tough. It's very tough.

这非常难. 实在太难了.

And you have to, first you have to convince yourself.

但这不得不做,首先你得说服你自己.

Then you have to convince your colleagues.

然后你必须去说服你的同事.

And then you have to convince the whole world

再然后你还得去说服整个世界

that you have actually detected something like this

你探测到一些

in the atmosphere of an extrasolar planet

类太阳主星的大气层中存在着某些东西

host star somewhere in 100 parsec away from here.

但这颗星离我们大概距离320光年(100秒差距).

It's really difficult.

这太难了.

But if you want to know about a life on extrasolar planets,

但如果你想了解外太阳系有没有生命,

you have to do this job.

你就必须做这些工作.

Because you have to know how much of radioactive element you have

因为你必须知道有多少放射性元素

in those systems.

存在于那些系统中.

The one way to discover about aliens

发现外星生命的一个方法

is to tune your radio telescope and listen to the signals.

就是调节你的射电望远镜并收听信号.

If you receive something interesting,

如果你接收到一些有趣的东西,

well that's what SETI does actually,

其实那是搜寻地外文明组织(SETI)去做的,

what SETI has been doing for many years.

他们一直做了很多年了.

I think the most promising way

我认为最有希望的方法

is to go for biomarkers.

就是用生物标志物.

You can see the spectrum of the Earth, this Earthshine spectrum,

你可以看一下地球的光谱,地球光线分析频谱.

and that is a very clear signal.

你能看到一个非常明确的信号.

The slope which is coming, which we call a Red Edge,

这个倾斜的地方我们称之为红边(Red Edge),

is a detection of vegetated area.

是植被区域的探测.

It's amazing that we can detect vegetation

这太神奇了,我们能从光谱中

from a spectrum.

检测出植物.

Now imagine doing this test

现在来想像一下探测

for other planets.

其他行星.

Now very recently, very recently,

最近,就在最近,

I'm talking about last six, seven, eight months,

我是说过去的七八个月,

water, methane, carbon dioxide

水,甲烷,二氧化碳

have been detected in the spectrum

已经在外太星系行星

of a planet outside the solar system.

的光谱中被发现.

It's amazing. So this is the power of spectroscopy.

这太棒了,这就是光谱的力量.

You can actually go and detect

你可以去探测

and study a chemical composition of planets

去研究行星的化学构成,

far, far, far from solar system.

既使离太阳系很远很远的地方.

We have to detect oxygen or ozone

我们还要检测氧气或者臭氧的含量

to make sure that we have all necessary conditions

来确定那里有所有必需条件

to have life.

有生命存在.

Cosmic miracles are something

宇宙的奇迹

which can be related to SETI.

与搜寻地外文明(SETI)紧密相关.

Now imagine an object, amazing object,

现在,想像有一个天体,神奇的天体,

or something which we cannot explain

或一些我们无法解释的天体

when we just stand up and say,

我们只是站起来说,

"Look, we give up. Physics doesn't work."

"好吧,我们放弃,物理学根本无法解释."

So it's something which you can always refer to SETI and say,

所以这就是你可以永远想着SETI说,

"Well, somebody must be doing this, somehow."

"好吧,肯定有某些人在用某种方法做这件事."

And with the known physics etc,

对于已知的物理学

it's something actually which has been pointed out

其实已经被一个学者指出来了

by Frank Drake,

是Frank Drake,

many years ago, and Shklovsky.

很多年以前.他就这么认为

If you see, in the spectrum of a planet host star,

如果你在一个主恒星系统中的行星的光谱中,

if you see strange chemical elements,

如果看到陌生的化学元素,

it can be a signal from a civilization

这可能是一个地外文明的发出的信号

which is there and they want to signal about it.

并且他们想要这个信号在那里存在.

They want to actually signal their presence

他们实际上想把他们的存在

through these spectral lines,

的信号存储在光谱条纹里,

in the spectrum of a star, in different ways.

用不同的方式表现在恒星的光谱中.

There can be different ways doing this.

他们可以用不同的方式去做这件事.

One is, for instance, technetium

举个例子, 例如锝元素

is a radioactive element

是一个放射性元素

with a decay time of 4.2 million years.

衰减周期大概是420万年.

If you suddenly observe technetium

如果你突然发现有锝元素存在于

in a sun-like star,

一个类太阳恒星中,

you can be sure that somebody has put this

你可以肯定是有人将这种元素放进了

element in the atmosphere,

这个大气层。

because in a natural way it is impossible to do this.

因为在自然界中不可能发生.

Now we are reviewing the spectra of about

现在我们正在查看光谱资料,

300 stars with extrasolar planets.

是关于300颗外太星系带行星的恒星.

And we are doing this job since 2000

我们从2000年就开始这项工作

and it's a very heavy project.

这是一项很复杂的工程.

We have been working very hard.

一直以为我们全力以赴.

And we have some interesting cases,

并且我们已经发现了一些有趣的例子,

candidates, so on, things which we can't really explain.

案例以及我们无法完全解释的东西.

And I hope in the near future

我希望在不久的将来

we can confirm this.

我们可以确定这些东西.

So the main question: "Are we alone?"

现在回到主要问题,"人类是孤独的吗?"

I think it will not come from UFOs.

我认为答案不会来自不明飞行物(UFO).

It will not come from radio signals.

也不是来自无线电信号.

I think it will come from a spectrum like this.

我认为答案将会从这些光谱中得到.

It is the spectrum of a planet like Earth,

这是一个类地行星的光谱

showing a presence of nitrogen dioxide,

有大量的氮氧化物

as a clear signal of life,

是生命存在的明显的信号,

and oxygen and ozone.

以及氧气和臭氧.

If, one day, and I think it will be

如果有这么一天,我想这一天将会是

within 15 years from now, or 20 years.

从现在开始的15年之内,或者20年之内.

If we discover a spectrum like this

如果我们发现有这样的光谱存在,

we can be sure that there is life on that planet.

可以肯定,那颗行星上存在生命.

In about five years we will discover

未来大约5年的时间我们将发现一些

planets like Earth, around sun-like stars,

类地行星环绕着类太阳恒星,

the same distance as the Earth from the Sun.

它们的距离相当于地球与太阳的距离.

It will take about five years.

大概花费五年的时间.

And then we will need another 10, 15 years

然后我们需要另外的10到15年时间

with space projects

通过空间工程

to get the spectra of Earth-like planets like the one I showed you.

来获得类地行星的光谱,如我刚展示给你的那张一样.

And if we see the nitrogen dioxide

如果我们看到有大量的氮氧化物

and oxygen,

和氧气存在,

I think we have the perfect E.T.

我认为我们就完美的找到了外星生命(E.T.)

Thank you very much.

非常感谢.

(Applause)

(掌声)