Distribution Of Galaxies托福听力原文翻译及问题答案

Distribution Of Galaxies托福听力原文翻译及问题答案

一、Distribution Of Galaxies 托福听力原文：

NARRATOR: Listen to part of a lecture in an astronomy class.

MALE PROFESSOR: Before we continue talking about the properties of individual galaxies, it's worth talking about the distribution of galaxies in space. Efforts at mapping, or surveying the universe, uh, making a sort of atlas of galaxies, have been going on for more than fifty years—and, um, the creators of the first major map of the universe were the astronomers Harlow Shapley and Adelaide Ames.

In 1932, Shapley and Ames catalogued the positions of 1,250 galaxies by photographing what they saw through their telescopes.

And they made an important discovery. Their survey was the first to indicate that galaxies were not distributed uniformly in space. Some areas had a lot of galaxies, and other areas had just a few. Uh, another way of putting this is to say that galaxies are clustered. They're not spread evenly throughout the universe. So we have stars grouped together in galaxies, and galaxies grouped together in clusters. OK?

Now, uh, after their survey, other astronomers completed surveys that added to the number of clusters catalogued.

One of the most important was done by the astronomer George Abell. Abell completed his survey in 1958. It added considerably to the map made by Shapley and Ames. In fact, his map had over 2,700 clusters of galaxies, that's 2,700 clusters of galaxies, not just galaxies.

But there's another aspect of Abell's work that makes this map so valuable to astronomers. He introduced a classification scheme for the galaxy clusters. Now, uh, surveys completed since Abell's have catalogued additional galaxies and surveyed more of outer space, but no one has improved upon Abell's classification scheme. In fact, the Abell catalogue is used as a starting point for astronomers who study these objects.

One of the reasons his scheme has been so widely accepted is because of his sample size. With all the clusters in his sample, he could determine the different characteristics of clusters. And these characteristics formed the basis of his classification scheme. Now, two of the characteristics crucial to his classification were richness and symmetry. So, ah, what did he mean by richness?

Well, basically it refers to the number of galaxies there are within a cluster.

FEMALE STUDENT: Is that the same as density?

MALE PROFESSOR: That’s right. Both, uh, “richness” and “density” refer to the number per area. Rich clusters, or dense clusters, uh, contain a relatively high number of galaxies.

FEMALE STUDENT: And symmetry just refers to its shape?

MALE PROFESSOR: Mm, roughly speaking, yes. Uh, whether the shape of the cluster was the same on the left side as on the right side.

So Abell used categories like that to classify clusters on a scale, from regular to irregular.

A “regular” cluster is sphere-shaped, symmetrical, and most dense in the middle, uh, with the greatest number of galaxies concentrated in the middle of the cluster.

An “irregular” cluster might appear to be lopsided, asymmetrical, with a low concentration of galaxies in the center.

FEMALE STUDENT: You're talking about the shape of the cluster though, not the shape of the galaxies within the cluster.

MALE PROFESSOR: Right. Uh, for example, let's consider the Coma cluster. It's a symmetrical cluster, basically spherical in shape. But the individual galaxies within it are elliptical. They're not spherical or spiral shaped. But the cluster itself shows spherical symmetry.

Um, the Virgo cluster, on the other hand, is considered irregular; there's no symmetry to its overall shape, no central concentration of galaxies. But it happens to have both elliptical and spiral galaxies within it.

FEMALE STUDENT: Another question—you were saying how some clusters have more galaxies than others—how many galaxies does a cluster have to have in order to even be a cluster?

MALE PROFESSOR: Good question.

Abell’s definition of a cluster is this.

First, there have to be more than fifty galaxies within a specific amount of space. He said basically that clusters have a radius of roughly 2 megaparsecs. And it was just an assumption, that all clusters would be about the same size. It's remarkable that it proved to be correct. And this “standard” cluster radius is known today as the Abell radius.

And second, those fifty-plus galaxies have to be a certain brightness. Of course, it was a rough estimate, but looking at galaxies' brightness was a good way to distinguish between clusters that were nearby and those that were more distant.

二、Distribution Of Galaxies 托福听力中文翻译：

旁白：在天文学课上听一节课的一部分。

男教授：在我们继续讨论单个星系的特性之前，有必要先讨论一下星系在空间中的分布。测绘或测量宇宙的努力，呃，制作一种星系地图册，已经进行了五十多年，第一张主要的宇宙地图的创造者是天文学家哈洛·夏普利和阿德莱德·艾姆斯。

1932年，Shapley和Ames通过拍摄他们通过望远镜看到的东西，对1250个星系的位置进行了编目。

他们有了一个重要的发现。他们的调查首次表明星系在空间中的分布并不均匀。一些区域有很多星系，而其他区域只有少数。呃，另一种说法是星系是集群的。它们并没有均匀地分布在整个宇宙中。所以我们有恒星在星系中聚集在一起，星系在星系团中聚集在一起。好啊

现在，呃，在他们的调查之后，其他天文学家完成了调查，增加了编目星团的数量。

其中最重要的一项研究是由天文学家乔治·阿贝尔完成的。阿贝尔于1958年完成了他的调查。这大大增加了Shapley和Ames绘制的地图。事实上，他的地图上有2700多个星系团，也就是2700个星系团，不仅仅是星系。

但阿贝尔工作的另一个方面使这张地图对天文学家如此有价值。他介绍了星系团的分类方案。现在，呃，自阿贝尔以来完成的调查已经对其他星系进行了编目，并调查了更多的外层空间，但没有人对阿贝尔的分类方案进行改进。事实上，阿贝尔目录是天文学家研究这些天体的起点。

他的方案被广泛接受的原因之一是他的样本量。利用样本中的所有簇，他可以确定簇的不同特征。这些特征构成了他的分类方案的基础。现在，对他的分类至关重要的两个特征是丰富性和对称性。那么，啊，他所说的富裕是什么意思？

基本上它指的是星系团中星系的数量。

女学生：这和密度一样吗？

男教授：没错。“丰富度”和“密度”都是指每个区域的数量。富星系团或致密星系团，呃，包含相对较多的星系。

女学生：对称就是指它的形状？

男教授：嗯，粗略地说，是的。呃，集群的形状在左侧和右侧是否相同。

所以Abell用这样的分类来对集群进行分类，从规则到不规则。

一个“规则”星系团是球状的，对称的，最密集的在中间，呃，最大数量的星系集中在星系团的中间。

一个“不规则”星系团可能看起来是不平衡的、不对称的，中心星系的浓度很低。

女学生：你说的是星系团的形状，而不是星系团中星系的形状。

男教授：对。呃，举个例子，让我们考虑一下昏迷团。它是一个对称的星团，基本上呈球形。但其中的单个星系是椭圆形的。它们不是球形或螺旋形的。但星团本身表现出球面对称性。

嗯，另一方面，室女座星团被认为是不规则的；它的整体形状没有对称性，没有集中的星系。但它碰巧有椭圆星系和旋涡星系。

女学生：另一个问题，你说的是为什么有些星系团比其他星系团有更多的星系，一个星系团要成为一个星系团，必须有多少个星系？

男教授：好问题。

Abell对集群的定义是这样的。

首先，在一定的空间范围内，必须有50多个星系。他说，基本上，集群的半径约为2兆帕斯卡。这只是一个假设，所有集群的大小都差不多。值得注意的是，它被证明是正确的。这个“标准”星团半径今天被称为阿贝尔半径。

其次，这五十多个星系必须有一定的亮度。当然，这是一个粗略的估计，但观察星系的亮度是区分附近星系团和较远星系团的一个好方法。

三、Distribution Of Galaxies 托福听力问题：

Q1:1.What is the main purpose of the lecture?

A. To explain the difficulty of classifying distant objects in the universe?

B. To introduce a classification system for galaxy clusters?

C. To present some recent discoveries about the shapes of galaxies?

D. To describe some differences between galaxies and clusters

Q2:2.What did Shapley and Ames discover about the universe?

A. Most galaxies are symmetrical.

B. More galaxies exist in the universe than was once believed.

C. Galaxies occur in clusters throughout the universe.

D. Clusters are distributed uniformly throughout the universe.

Q3:3.Why does the professor emphasize the number of clusters mapped by Abell?

A. To help explain why Abell's classification scheme was widely adopted

B. To explain why Abell was the first astronomer to notice spiral-shaped galaxies

C. To provide evidence that Abell's method of surveying galaxies was superior to that used for previous surveys

D. To show how much Abell relied on earlier research

Q4:4.What aspects of clusters did Abell use to classify them? [Click on 2 answers. ]

A. The density of the cluster

B. The shape of the cluster

C. The age of the cluster

D. The type of galaxies in the cluster

Q5:5.Why does the professor discuss the Coma and Virgo clusters?

A. To indicate a limitation of Abell's survey

B. To distinguish between rich and non-rich clusters

C. To demonstrate that clusters considered irregular in shape are basically spherical

D. To illustrate that the shape of a cluster is independent of the shape of the galaxies within it

Q6:6.What is the professor's opinion of Abell's assumption that all clusters are about the same size?

A. He is surprised that it has been disproved.

B. He believes that there is not enough data to support it.

C. He is impressed that it has been proved correct.

D. He thinks it is Abell's most important contribution to astronomy.

四、Distribution Of Galaxies 托福听力答案：

A1:正确答案：B

A2:正确答案：C

A3:正确答案：A

A4:正确答案：AB

A5:正确答案：D

A6:正确答案：C

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