第六篇:暗物质的测定 第一段说,天文学家们最近开始观察某东西MACHO(massive compact halo objects),然后介绍它一堆特性。我感觉我没仔细看这段,应该没啥题,因为没啥印象。 第二段说,传统的探测g物质的方法不能用了,得用新方法,如果天文学家正在看某星星,这个MACHO物质如果刚好穿过了就能看到,有光。 第三段说,天文学家发现说,MACHO物质在galaxy之内的数量比想象中多,但是没有更多的更深入的研究,天文学家就不会冒昧的猜测它的数量之类的。 Q1天文学家之前没有预料到啥? 答:选那个galaxy之下数量比想象中多。 Q2天文学家提到XX-effecience是为了说明什么 定位这个高亮单词的前面一点,态度很明确的, Q3天文爱好者为什么对dark物质感兴趣(即测定暗物质的目的)? 因为可以dark物质account for宇宙的大部分质量 Q4为什么要改进观测方法? 因为他们不知道现在overestimated多少 Q5第三段谈乱观测方法强转折处有题。 Q6科学家为什么要研究黑洞, 因为他们觉得黑洞可能组成了宇宙间大部分的物质的重量, (750) Q7考以下哪种情况不是科学家预先假设的, 这题在A和B中我不确定,因为时间比较紧来不及仔细看,原文应该能找到. A选项是黑洞的不规则的SIZE和***** B选项是microlensing这个现象大多发生在galaxy的中心,我猜了B但是感觉不对, (750) Q8好象说以下哪个不是事实, 我选的是科学家认为microlensing大多发生在宇宙边缘(还是中心?忘记了),定位在原文的最后一句话(750) Stava说,本文章需要注意的地方在对dark的观测。 Q9主题,我选的是说describe 了一个新的发现什么的。反正没有态度词的选项 In the 1980's, astronomer BohdanPaczynski proposed a way of determining whether the enormous dark haloconstituting the outermost part of the Milky Way galaxy is composed of MACHO's(massive compact halo objects), which are astronomical objects too dim to bevisible.
Paczynski reasoned that ifMACHO's make up this halo, a MACHO would occasionally drift in front of a starin 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 otherwisediverge, to bend together so that, as observed from Earth, the star wouldtemporarily appear to brighten, a process known as microlensing.
Because many individual stars are ofintrinsically variable brightness, some astronomers have contended that the brighteningof intrinsically variable stars can be mistaken for microlensing.
However, whereas the different colors oflight emitted by an intrinsically variable star are affected differently whenthe star brightens, all of a star's colors are equally affected bymicrolensing.
Thus, if a MACHO magnifiesa star's red light tenfold, it will do the same to the star's blue light andyellow light.
Moreover, it is highlyunlikely that a star in the Large Magellanic Cloud will undergo microlensingmore than once, because the chance that a second MACHO would pass in front ofexactly the same star is minuscule. Question #55.
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(23881-!-item-!-188;#058&000639-01) It can be inferred from the passagethat which of the following would constitute the strongest evidence of themicrolensing of a star in the Large Magellanic Cloud? (A) The brightness of such a staris observed to vary at irregular intervals. (B) The brightening of such a staris observed to be of shorter duration than the brightening of neighboringstars. (C) The red light of such a star isobserved 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 thesame factor. (E) The red light of such a star isobserved to have increased tenfold. Question #56.
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(23927-!-item-!-188;#058&000639-04) According to the passage,Paczynski's theory presumes that if MACHO's constituted the Milky Way's darkhalo, occasionally a MACHO would (A) drift so as to lie in a directline between two stars in the outer Milky Way (B) affect the light rays of a starin the Large Magellanic Cloud with the result that the star would seem for atime to brighten (C) become obscured as a result ofthe microlensing of a star in the Large Magellanic Cloud (D) temporarily increase theapparent brightness of a star in the Large Magellanic Cloud by increasing thegravity of the star (E) magnify each color in thespectrum of a star in the Large Magellanic Cloud by a different amount Question #57.
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(23973-!-item-!-188;#058&000639-06) The passage is primarily concernedwith (A) outlining reasons why aparticular theory is no longer credited by some astronomers (B) presenting data collected by aresearcher in response to some astronomers' criticism of a particular line ofreasoning (C) explaining why a researcherproposed a particular theory and illustrating how influential that theory hasbeen (D) showing how a researcher'stheory has been used to settle a dispute between the researcher and someastronomers (E) describing a line of reasoningput forth by a researcher and addressing a contention concerning that line ofreasoning V2 第一段讲:宇宙中大家知道的物质只占了5%,剩下的都是暗物质.剩下的不记得了.第一段没什么出题点
第二段:提问,暗物质是由什么组成的?P和N不是,接下来是"Nor can more than a few of Neutrino怎么怎么的,意思是Neutrino也不是暗物质. 接下来高亮"一个关于newtrino的实验,说它很轻啦,速度很快啦,因此很hot "总之也不是dark matter.
第三段: 记得个fit的词(我理解是根据以上neutrino特征的反面推出的dark matter的特征), 能fit dark matter的物质具有的特点是cold, sluggish等等. 貌似在现在的cosmatic中不存在,但是在standard的假说中有一种neutranilo的物质符合
第四段: 主要讲neutronilo的,这里提到它不被electromagnetic怎么着(在比较俩个N不同的选项里出现),同时它又是最轻的,它又很stable, 因为如果不够轻的话就会不stable从而被分成俩个更轻的(很绕的逻辑),
第二段和第四段非常长,而且有很多细节题.
Q1高亮的实验的作用
记得的选项是:1,回答段首的问题.2,支持前面那句话"nor more than".3,为了第三段什么的.我选了第二个.
Q2Neutrino 和 neutranilo的描述哪个正确(以下简称n1,n2)
1,n2在宇宙初期不被electromagnetic影响(我犹豫了下,文中是提到有,但是没有前面的宇宙初期的限定,我没选)
2,n2比n1重.(我选的这个)
3,n1不stable(文中没提)
4,n2在cosmic中实际上还没被发现?(我排除了) 另一篇自然科学类的,讲的是科学家认为宇宙中可以观测到的(visible)的那些星体啊,gas啊什么的,只占到整个宇宙mass的10%。另外90%都是一些invisible的物质,叫什么halo (文章一开头据开门见山的提到了这种“black massive 。。。”的东西)。然后说科学家估计这种物种在星系的周围有很多(surrounding of galaxies)。第二段开始讲,传统的观测方法是探测不到这些物质的 (当然咯,都说了是invisible了嘛),有一种方法,就是当这些物质运动到一些stars的旁边,就是这个物质正好处在stars和观测者之间的时候,它会是star发出的光线弯曲或者其他变化什么的,于是就从侧面证明确实是有一种物质存在,干扰了这些光线。这种曲线救国的方法叫microlensing……好像是……记不清楚了!!!!第三段讲,从第一次观测到这个现象以后,这个现象出现的次数少于预期。科学家于是目前不愿意做出puplic的预测,到底有到少这样的物质。最后说,可以明确的是这种物质在星系中间存在较多,因为这个现象多出现于星系中间。 V3 12M行星的研究:
12.1文章较长,但是很简单易懂。说天文学家最近研究了M开头的行星,使用的方法是观察法,因为每当M行星靠近其它恒星的时候,由于引力和其它物理作用,其它恒星会有一段时间异常发亮。目前天文学家发现的大部分M行星都位于galaxy中部,他们推测其它主体的M行星可能在outer space。另外由于观察法的limited effectiveness(后面有题),天文学家对于到底有多少M行星表示不确定 |