【3月16日阅读答案】

belinda_cao · 发表于 2014-3-16 17:57:02

【3月16日阅读】

【长难句二句】
1）Possibly as numerous as conventional galaxies, these galaxies have the same general shape and even the same approximate number of stars as a common type of conventional galaxy, the spiral, but tend to be much larger

2）Baryons—subatomic particles that are generally protons or neutrons—are the source of stellar, and therefore galactic, luminosity, and so their numbers can be estimated based on how luminous galaxies are

In addition to conventional galaxies, the universe contains very dim galaxies that until recently went unnoticed by astronomers. Possibly as numerous as conventional galaxies, these galaxies have the same general shape and even the same approximate number of stars as a common type of conventional galaxy, the spiral, but tend to be much larger. Because these galaxies’ mass is spread out over larger areas, they have far fewer stars per unit volume than do conventional galaxies. Apparently these low-surface-brightness galaxies, as they are called, take much longer than conventional galaxies to condense their primordial gas and convert it to stars—that is, they evolve much more slowly.
词汇：dim 暗淡的， astronomer 天文学家，until 到.....止，galaxies 星系，approximate接近， spiral 螺旋、漩涡，spread out 延长
直到最近天文学家才发现，除了常规的星系之外，宇宙中还存在非常暗淡的星系。这些星系有可能和常规星系一样多，他们的形状和拥有星星的大致数量都和常规漩涡星系无异，但是星系可能更大。因为这些星系所占的面积很大，所以他们每一单位体积的星星比常规星系更少。很明显这些表面暗淡的星系，名如其实，比常规星系需要更长的时间来聚集他们的原始气体并将其转化为星星，也就是说，他们进化得很慢。

These galaxies may constitute an answer to the long-standing puzzle of the missing baryonic mass in the universe. Baryons—subatomic particles that are generally protons or neutrons—are the source of stellar, and therefore galactic, luminosity, and so their numbers can be estimated based on how luminous galaxies are. However, the amount of helium in the universe, as measured by spectroscopy, suggests that there are far more baryons in the universe than estimates based on
galactic luminosity indicate. Astronomers have long speculated that the missing baryonic mass might eventually be discovered in intergalactic space or as some large population of galaxies that are difficult to detect.
词汇：baryon 重子 subatomic 次原子的，protons 质子， stellar 星球，galactic 银河的，luminosity 发光体，helium 氦，
这些星系也许能解释宇宙中“消失的”重子质量这个长期困扰着科学界的问题。重子即亚原子颗粒，一般由质子或者中子构成。而质子和中子是恒星的来源，并因此产生了星系和光源，所以他们的数量可以根据星系的亮度来测定。然而，那通过光谱学测量出来的宇宙中氦气的数量却显示：在宇宙中存在着比发光的星系显示出来的数量更多的重子。天文学家们长期猜测这些“消失的”重子有可能存在于星系间的空隙或者作为难以察觉的星系被发现

PIE structure:
paragraph 1:
P:宇宙中存在暗淡的星系
I1:这些星系和常规星系有几个区别与相似点：**相似点：形状、数量多少和拥有星星的数量；**不同点：每单位体积拥有的星星比常规星系少
I2:暗淡的星系进化慢
paragraph2:
P:暗淡星系可以解释“消失的”重子质量去哪儿了这个问题
I：重子是发光星系的源泉，而通过光谱学测量显示宇宙中应有的重子数量远远多于现在我们仅仅通过发光星系能测量出来的数量，天文学家曾一度认为他们就隐藏在星际间隙或作为难以察觉的星系被发现。

【3月16日阅读答案】

所属分类: GMAT考试

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