科学美国人60秒 SSS 天文学家发现宇宙初期的两个“隐形”星系

This is Scientific American’s 60-Second Science. I’m Christopher Intagliata.

这里是科学美国人——60秒科学系列，我是克里斯托弗·因塔利亚塔。

If you’ve ever looked up at the Milky¹ Way, you’ve seen what’s known as cosmic dust.

如果你曾经仰望过银河系，你就会看到所谓的宇宙尘埃。

When you see this band of the Milky Way, you can see these dark patches.

当你观察银河系的光带时，你可以看到这些深色的斑块。

So that’s really just dust that is obscuring the stars behind it.

所以这些尘埃掩盖了它后边的恒星。

Pascal Oesch is an associate professor at the University of Geneva.

帕斯卡·奥什是日内瓦大学的副教授。

He points out that cosmic dust isn’t exactly the kind of dust you or I might be familiar with.

他指出宇宙尘埃并不是你我所熟悉的那种尘埃。

Cosmic dust is not quite the same as dust we know from the apartment here.

宇宙尘埃和我们在这间公寓里看到的尘埃并不完全一样。

Cosmic dust is really just very small particles in the universe that are consisting of just a few molecules², often containing carbon or silicate³.

宇宙尘埃实际上是宇宙中非常小的粒子，仅由几个微粒组成，通常含有碳或硅酸盐。

And—as in that Milky Way example—that cosmic dust absorbs the light of stars behind it, making it harder for us to see those stars with instruments like the Hubble Space Telescope.

而且，就和银河系的例子一样，宇宙尘埃吸收了它背后恒星的光，使我们很难用哈勃空间望远镜等仪器看到这些恒星。

But there is one way around that: Astronomers⁴ can observe the sky with longer wavelengths⁵—using telescopes like the Atacama Large Millimeter/submillimeter Array in Chile, or ALMA.

但有一种方法可以解决这个问题:天文学家可以用更长的波长来观测天空——使用像智利阿塔卡马大型毫米波天线阵(ALMA)这样的望远镜。

With ALMA, astronomers can see even the dust bunnies hiding up in the sky—because as the dust absorbs photons from the stars behind it, it heats up.

使用ALMA，天文学家甚至可以观察到隐藏在天空中的尘埃，因为当尘埃从它后面的恒星吸收光子时，它会升温。

And so then, with ALMA, we can directly see the emission⁶ of this heated up dust even in the very early universe.

因此，通过ALMA，我们可以直接观察到这些升温尘埃发热，即使是在宇宙早期。

Oesch and his team have now stumbled upon two previously⁷ obscured galaxies⁸ using ALMA observations.

现在，奥什和他的团队使用ALMA观测偶然发现了两个之前被遮挡的星系。

The galaxies date back to the very earliest days of the universe, 13 billion years ago.

这些星系可以追溯到宇宙最早期，即130亿年前。

So those are the first building blocks, right, of the galaxies that we see around us in the universe today.

所以这些是我们今天在宇宙中看到的星系的第一个组成部分。

So these are the first kind of Lego stones. And apparently⁹ we have been missing some of those Lego stones.

这些是第一批乐高积木。很明显，我们已经缺失了一些乐高积木。

In fact, the scientists estimate that up to one in five galaxies may be missing from our current census¹⁰ of the early universe.

事实上，科学家们估计，多达五分之一的星系可能从我们当前的早期宇宙普查中消失。

The results appeared recently in the journal Nature.

研究结果最近发表在《自然》期刊上。

Hubble's successor, the James Webb Space Telescope, is set to sail off the planet later this month.

哈勃望远镜的继任者，詹姆斯·韦伯空间望远镜，将于本月晚些时候驶离地球。

And with its more powerful ability to probe long wavelengths, Oesch is hoping it might bring our galactic census a little closer to completion.

詹姆斯·韦伯空间望远镜拥有更强大的探测长波的能力，奥什希望它能让完成银河系普查更进一步。

Thanks for listening for Scientific American's 60-second Science. I'm Christopher Intagliata.

谢谢大家收听科学美国人——60秒科学。我是克里斯托弗·因塔利亚塔。

1 milky   

adj.牛奶的，多奶的；乳白色的

参考例句：

• Alexander always has milky coffee at lunchtime.亚历山大总是在午餐时喝掺奶的咖啡。
• I like a hot milky drink at bedtime.我喜欢睡前喝杯热奶饮料。

2 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。

3 silicate   

n.硅酸盐

参考例句：

• There are large amounts of aluminum silicate in the area.这个地区有大量的硅酸铝。
• Silicate minerals are characteristically refractory and difficult to break down.硅酸盐矿物的特点是耐熔和难以分离。

4 astronomers   

n.天文学者，天文学家( astronomer的名词复数 )

参考例句：

• Astronomers can accurately foretell the date,time,and length of future eclipses. 天文学家能精确地预告未来日食月食的日期、时刻和时长。 来自《简明英汉词典》
• Astronomers used to ask why only Saturn has rings. 天文学家们过去一直感到奇怪，为什么只有土星有光环。 来自《简明英汉词典》

5 wavelengths   

n.波长( wavelength的名词复数 )；具有相同的/不同的思路；合拍；不合拍

参考例句：

• I find him difficult to talk to—we're on completely different wavelengths. 我没法和他谈话，因为我们俩完全不对路。 来自《简明英汉词典》
• Sunlight consists of different wavelengths of radiation. 阳光由几种不同波长的射线组成。 来自辞典例句

6 emission   

n.发出物，散发物；发出，散发

参考例句：

• Rigorous measures will be taken to reduce the total pollutant emission.采取严格有力措施，降低污染物排放总量。
• Finally,the way to effectively control particulate emission is pointed out.最后，指出有效降低颗粒排放的方向。

7 previously   

adv.以前，先前（地）

参考例句：

• The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
• Let me digress for a moment and explain what had happened previously.让我岔开一会儿，解释原先发生了什么。

8 galaxies   

星系( galaxy的名词复数 )； 银河系； 一群（杰出或著名的人物）

参考例句：

• Quasars are the highly energetic cores of distant galaxies. 类星体是遥远星系的极为活跃的核心体。
• We still don't know how many galaxies there are in the universe. 我们还不知道宇宙中有多少个星系。

9 apparently   

adv.显然地；表面上，似乎

参考例句：

• An apparently blind alley leads suddenly into an open space.山穷水尽，豁然开朗。
• He was apparently much surprised at the news.他对那个消息显然感到十分惊异。

10 census   

n.(官方的)人口调查，人口普查

参考例句：

• A census of population is taken every ten years.人口普查每10年进行一次。
• The census is taken one time every four years in our country.我国每四年一次人口普查。