关于宇宙暗物质的那道题谁帮我补充一下?

norinfo

好似有个CDer提供了下面的信息, 不知道是否有补充的.

宇宙的一种现象的解释
        （为什么这个月那么多宇宙题？！其实这篇文章中的一个专有名词Microlense在MACHO暗物质里也出现-是不是出题者的疏忽？）（两端） 

段一： S体重对一种现象的解释。什么物体是由于galaxy G1穿过哪个重力场（gravity field）Q017981（一串数字）造成的亮度减少（这个现象的陈述没有考点，虽然很难读，但是完全不需要理解）。并且S相信这个物体的体积越小(mass)，这个现象的时间越短（还是越什么来着）（考点2）。
         

段二：之后他说由于这个现象通常持续数十年(decades)，而他的观察只有几个星期，所以他的理论有个什么什么缺陷（没有考点）。Tuner（另外一个天文学家，估计是）说现象可能不是由于那个物体产生的。Gould（再另外一个天文学家）说现象可能是由于disk（碟状星云之类的东西吧）与星云之间的作用。S跳出来说G的反驳无理，因为碟状星云在旋转的时候那个重力被抵消了。
            

 

问题一：忘记了
            

问题二：S会同意什么：就是考点2所在。
            

问题三：S为什么反对G的观点：因为重力被抵消

急，感谢！

myheart2008

不知道是不是这个，PREP里的

In the 1980's, astronomer Bohdan Paczynski proposed a way of determining whether the enormous dark halo constituting the outermost part of the Milky Way galaxy is composed of MACHO's (massive compact halo objects), which are astronomical objects too dim to be visible.  Paczynski reasoned that if MACHO's make up this halo, a MACHO would occasionally drift in front of a star in the Large Magellanic Cloud, a bright galaxy near the Milky Way.  The gravity of a MACHO that had so drifted, astronomers agree, would cause the star's light rays, which would otherwise diverge, to bend together so that, as observed from Earth, the star would temporarily appear to brighten, a process known as microlensing.  Because many individual stars are of intrinsically variable brightness, some astronomers have contended that the brightening of intrinsically variable stars can be mistaken for microlensing.  However, whereas the different colors of light emitted by an intrinsically variable star are affected differently when the star brightens, all of a star's colors are equally affected by microlensing.  Thus, if a MACHO magnifies a star's red light tenfold, it will do the same to the star's blue light and yellow light.  Moreover, it is highly unlikely that a star in the Large Magellanic Cloud will undergo microlensing more than once, because the chance that a second MACHO would pass in front of exactly the same star is minuscule.

saku734

以下是引用myheart2008在2008-6-11 23:07:00的发言：

不知道是不是这个，PREP里的

In the 1980's, astronomer Bohdan Paczynski proposed a way of determining whether the enormous dark halo constituting the outermost part of the Milky Way galaxy is composed of MACHO's (massive compact halo objects), which are astronomical objects too dim to be visible.  Paczynski reasoned that if MACHO's make up this halo, a MACHO would occasionally drift in front of a star in the Large Magellanic Cloud, a bright galaxy near the Milky Way.  The gravity of a MACHO that had so drifted, astronomers agree, would cause the star's light rays, which would otherwise diverge, to bend together so that, as observed from Earth, the star would temporarily appear to brighten, a process known as microlensing.  Because many individual stars are of intrinsically variable brightness, some astronomers have contended that the brightening of intrinsically variable stars can be mistaken for microlensing.  However, whereas the different colors of light emitted by an intrinsically variable star are affected differently when the star brightens, all of a star's colors are equally affected by microlensing.  Thus, if a MACHO magnifies a star's red light tenfold, it will do the same to the star's blue light and yellow light.  Moreover, it is highly unlikely that a star in the Large Magellanic Cloud will undergo microlensing more than once, because the chance that a second MACHO would pass in front of exactly the same star is minuscule.

不是这个。

但这里讲的内容与暗物质那篇里的部分内容基本是一样的。

nedelon

题目能补充下么？？

lyricsea

楼主，以下的内容才是暗物质那篇，你的那个是后来一篇关于宇宙现象的新的JJ。暂时貌似只有stavan考到了。。是stavan考到的吧，我不知道有没有记错。。。。

第一段讲宇宙存在一种物质，dark。本来科学家以为暗物质密集在星系中心，后来由于一种方法(microbenting好像是这么写的，即光线曲折——暗物质本身无法被观察到，但是就像月食日食一样，如果它经过另一个发光的星星，科学家就能察觉到它了)，科学家发现其实是星系边缘有大量暗物质。密度跟行星差不多，这个东西在宇宙中应该占据绝大部分质量，是太阳的1/10 占宇宙重量的90%  balabala。主要介绍定义和目的。

第二段讲观测，说传统方法很难观测到，天文爱好者观测 dark物质通过他们和发亮的星星之间是时产生的一种类似于日食（及光亮度下降）的现象，定义现象A

第三段讲观测到的A明显比预计的要多，作者的态度并不是很肯定，而且星系内部的暗物质似乎大于外部的，与以前的估计相左。说他们的观测方法需要改进，而且在改进之前他们并不愿意公开他们的研究结果。在谈论观测方法时，有强转折（此处有题）。

问题1、
  天文爱好者为什么对dark物质感兴趣（即测定暗物质的目的）？我选的：因为可以dark物质account for宇宙的大部分质量

问题2、为什么要改进观测方法？
  我选的：因为他们不知道现在overestimated多少

问题3、第三段谈乱观测方法强转折处有题。

[此贴子已经被作者于2008-6-11 23:55:34编辑过]

beyond1128

没下到prep阅读，很茫然，我这只有数学和SC....
能否发下上面那篇的问题及答案阿

lyricsea

beyond1128。。。楼下是这篇prep的，确实讲的有同一个物质，可以参考

Essay #17.  639     (23835-!-item-!-188;#058&00639-00)

 

In the 1980's, astronomer Bohdan Paczynski proposed a way of determining whether the enormous dark halo constituting the outermost part of the Milky Way galaxy is composed of MACHO's (massive compact halo objects), which are astronomical objects too dim to be visible.  Paczynski reasoned that if MACHO's make up this halo, a MACHO would occasionally drift in front of a star in the Large Magellanic Cloud, a bright galaxy near the Milky Way.  The gravity of a MACHO that had so drifted, astronomers agree, would cause the star's light rays, which would otherwise diverge, to bend together so that, as observed from Earth, the star would temporarily appear to brighten, a process known as microlensing.  Because many individual stars are of intrinsically variable brightness, some astronomers have contended that the brightening of intrinsically variable stars can be mistaken for microlensing.  However, whereas the different colors of light emitted by an intrinsically variable star are affected differently when the star brightens, all of a star's colors are equally affected by microlensing.  Thus, if a MACHO magnifies a star's red light tenfold, it will do the same to the star's blue light and yellow light.  Moreover, it is highly unlikely that a star in the Large Magellanic Cloud will undergo microlensing more than once, because the chance that a second MACHO would pass in front of exactly the same star is minuscule.

 

Question #55.  639-01
                (23881-!-item-!-188;#058&000639-01)

 

It can be inferred from the passage that which of the following would constitute the strongest evidence of the microlensing of a star in the Large Magellanic Cloud?

 

(A) The brightness of such a star is observed to vary at irregular intervals.

(B) The brightening of such a star is observed to be of shorter duration than the brightening of neighboring stars.

(C) The red light of such a star is observed to be brighter than its yellow light and its blue light.

(D) The red light, yellow light, and blue light of such a star are observed to be magnified temporarily by the same factor.

(E) The red light of such a star is observed to have increased tenfold.

 

Question #56.  639-04
                (23927-!-item-!-188;#058&000639-04)

 

According to the passage, Paczynski's theory presumes that if MACHO's constituted the Milky Way's dark halo, occasionally a MACHO would

 

(A) drift so as to lie in a direct line between two stars in the outer Milky Way

(B) affect the light rays of a star in the Large Magellanic Cloud with the result that the star would seem for a time to brighten

(C) become obscured as a result of the microlensing of a star in the Large Magellanic Cloud

(D) temporarily increase the apparent brightness of a star in the Large Magellanic Cloud by increasing the gravity of the star

(E) magnify each color in the spectrum of a star in the Large Magellanic Cloud by a different amount

 

Question #57.  639-06
                (23973-!-item-!-188;#058&000639-06)

 

The passage is primarily concerned with

 

(A) outlining reasons why a particular theory is no longer credited by some astronomers

(B) presenting data collected by a researcher in response to some astronomers' criticism of a particular line of reasoning

(C) explaining why a researcher proposed a particular theory and illustrating how influential that theory has been

(D) showing how a researcher's theory has been used to settle a dispute between the researcher and some astronomers

(E) describing a line of reasoning put forth by a researcher and addressing a contention concerning that line of reasoning

 

beyond1128

lyricsea，好人呐~~~感谢！！！

nedelon

谁说说一个人大方慷慨要用大陆。。大海更加宽广么。。歌词海你太海了。/。