国际顶尖MBA申请交流平台--TOPWAY MBA

标题: 大全33 [打印本页]

作者: anchoretes 时间: 2010-7-19 07:07 标题: 大全33

Passage 33 (33/63)

Until recently most astronomers believed that the space between the galaxies in our universe was a near-perfect vacuum. This orthodox view of the universe is now being challenged by astronomers who believe that a heavy “rain” of gas is falling into many galaxies from the supposedly empty space around them. The gas apparently condenses into a collection of small stars, each a little larger than the planet Jupiter. These stars vastly outnumber the other stars in a given galaxy. The amount of “intergalactic rainfall” into some of these galaxies has been enough to double their mass in the time since they formed. Scientists have begun to suspect that this intergalactic gas is probably a mixture of gases left over from the “big bang” when the galaxies were formed and gas was forced out of galaxies by supernova explosions.

It is well known that when gas is cooled at a constant pressure its volume decreases. Thus, the physicist Fabian reasoned that as intergalactic gas cools, the cooler gas shrinks inward toward the center of the galaxy. Meanwhile its place is taken by hotter intergalactic gas from farther out on the edge of the galaxy, which cools as it is compressed and flows into the galaxy. The net result is a continuous flow of gas, starting as hot gases in intergalactic space and ending as a drizzle of cool gas called a “cooling flow,” falling into the central galaxy.

A fairly heretical idea in the 1970’s, the cooling-flow theory gained support when Fabian observed a cluster of galaxies in the constellation Perseus and found the central galaxy, NGC 1275, to be a strange-looking object with irregular, thin strands of gas radiating from it. According to previous speculation, these strands were gases that had been blown out by an explosion in the galaxy. Fabian, however, disagreed. Because the strands of gas radiating from NGC 1275 are visible in optical photographs, Fabian suggested that such strands consisted not of gas blown out of the galaxy but of cooling flows of gas streaming inward. He noted that the wavelengths of the radiation emitted by a gas would changes as the gas cooled, so that as the gas flowed into the galaxy and became cooler, it would emit not x-rays, but visible light, like that which was captured in the photographs. Fabian’s hypothesis was supported by Canizares’ determination in 1982 that most of the gas in the Perseus cluster was at a temperature of 80 million degrees Kelvin, whereas the gas immediately surrounding NGC 1275 (the subject of the photographs) was at one-tenth this temperature.

我读原文的意思, 好象是说intergalaxy (也就是galaxy以外)的温度热, 而galaxy中心的温度冷. 可是文章最后一句的意思好象是说Perseus galaxy中心比外面热.

请NN帮忙分析一下.

作者: hangtianyuan 时间: 2010-7-19 19:59

Passage 33 (33/63)

Until recently most astronomers believed that the space between the galaxies in our universe was a near-perfect vacuum.
天文学家一直认为星系间接近真空。

This orthodox view of the universe is now being challenged by astronomers who believe that a heavy “rain” of gas is falling into many galaxies from the supposedly empty space around them.
现在，天文学家相信有气体"雨"分布其间。

The gas apparently condenses into a collection of small stars, each a little larger than the planet Jupiter.
这种气体凝聚成一系列的小星体，每一个都稍大于木星(是木星吧，没有记准)。

These stars vastly outnumber the other stars in a given galaxy.
数目众多，比在星系里的星还多。

The amount of “intergalactic rainfall” into some of these galaxies has been enough to double their mass in the time since they formed.
落入一些星系的“星系间雨幕”的质量足以使这些星系的质量倍增。

Scientists have begun to suspect that this intergalactic gas is probably a mixture of gases left over from the “big bang” when the galaxies were formed and gas was forced out of galaxies by supernova explosions.
有怀疑指，星系间气体是宇宙大爆炸留下的气体混合物。当时，星系形成，超新星爆炸将气体挤出星系。

It is well known that when gas is cooled at a constant pressure its volume decreases.
衡压下，气体冷却，体积减少。

Thus, the physicist Fabian reasoned that as intergalactic gas cools, the cooler gas shrinks inward toward the center of the galaxy.
Fabian推理，星系间气体冷却，气体向星系中心压缩。

Meanwhile its place is taken by hotter intergalactic gas from farther out on the edge of the galaxy, which cools as it is compressed and flows into the galaxy.
同时，其位置被离星系边缘更遥远的较热气体所占据。这些较热气体边压缩边冷却，并流向星系。

The net result is a continuous flow of gas, starting as hot gases in intergalactic space and ending as a drizzle of cool gas called a “cooling flow,” falling into the central galaxy.
直接结果是气体的连续流动，一开始是星系间的热气，最后成为一股冷气，即“冷流”，流向中心星系。

A fairly heretical idea in the 1970’s, the cooling-flow theory gained support when Fabian observed a cluster of galaxies in the constellation Perseus and found the central galaxy, NGC 1275, to be a strange-looking object with irregular, thin strands of gas radiating from it.
冷流理论在1970年代被视为异端想法，但被F的观察所支持。

According to previous speculation, these strands were gases that had been blown out by an explosion in the galaxy.
据前推测，这些气体带曾被星系内的爆炸喷出。

Fabian, however, disagreed.
但F不同意。

Because the strands of gas radiating from NGC 1275 are visible in optical photographs, Fabian suggested that such strands consisted not of gas blown out of the galaxy but of cooling flows of gas streaming inward.
因为是可见光，所以F认为这些气体带不仅有喷出的，也有流入的冷流。（听取joeysue的意见。前面的翻译有误，改成“这些气体带不是喷出的，而是流入的冷流。”）

He noted that the wavelengths of the radiation emitted by a gas would changes as the gas cooled, so that as the gas flowed into the galaxy and became cooler, it would emit not x-rays, but visible light, like that which was captured in the photographs.
他推理到，冷流可发出可见光。

Fabian’s hypothesis was supported by Canizares’ determination in 1982 that most of the gas in the Perseus cluster was at a temperature of 80 million degrees Kelvin, whereas the gas immediately surrounding NGC 1275 (the subject of the photographs) was at one-tenth this temperature.
F的理论在1982年被C所支持，P星座(星系群)中的气体(即星系间气体)温度8千万K读，而NGG 1275这一星系的周边气体温度为8百万K度。

哈哈，文章还是挺有意思的。这些原本看不到的气体，温度如此之高啊!

希望最后一句的星座和星系的差别能够解决楼主的问题.

作者: anchoretes 时间: 2010-7-20 07:04

谢谢LZ的细心解释. 对文章其中几句话, 我还是不太理解.

Meanwhile its place is taken by hotter intergalactic gas from farther out on the edge of the galaxy, which cools as it is compressed and flows into the galaxy.

The net result is a continuous flow of gas, starting as hot gases in intergalactic space and ending as a drizzle of cool gas called a “cooling flow,” falling into the central galaxy.

也就是说intergalactic的气温高. 而galaxy边缘的气温低. 而galaxy中间的气温更低.

Fabian’s hypothesis was supported by Canizares’ determination in 1982 that most of the gas in the Perseus cluster was at a temperature of 80 million degrees Kelvin, whereas the gas immediately surrounding NGC 1275 (the subject of the photographs) was at one-tenth this temperature.

证据是反的. 它说明galaxy中间的气温高, 而galaxy边缘的气温低. 这样的反例怎么可以证明F的理论呢?

是不是我理解有误. 请指教.

作者: hangtianyuan 时间: 2010-7-20 20:06

谢谢LZ的细心解释. 对文章其中几句话, 我还是不太理解.

Meanwhile its place is taken by hotter interg ...
anchoretes 发表于 2010-7-20 07:04

它说明galaxy中间的气温高, 而galaxy边缘的气温低. 这样的反例怎么可以证明F的理论呢?

还是应理解我上贴的最后一句话。Perseus Cluster是一个星座，是由很多很多星系组成的星座(此点文中有论述)。而NGC1275是其中的一个星系。星座P内的大部分气体，即星系间气体，温度高。星系NGC1275周围紧邻的气体，温度低。这与冷流理论一致。

作者: xiaoaojiang 时间: 2010-7-21 06:39

“Because the strands of gas radiating from NGC 1275 are visible in optical photographs, Fabian suggested that such strands consisted not of gas blown out of the galaxy but of cooling flows of gas streaming inward.”
因为是可见光，所以F认为这些气体带不仅有喷出的，也有流入的冷流。

这里是翻译成不仅吗？但那里是not but 不是not only but also，但按not but 翻又不对，逻辑上按不但而且要更合理。请教wangyu，这种情况如何判断呢？

作者: hangtianyuan 时间: 2010-7-21 19:32

是啊，我认为，我搞错了。应当是“不是...，而是..."。这样才说明了F的观点。

作者: IMARCUS 时间: 2010-7-22 19:55

我想问一下，这个According to previous speculation里的speculation指的是Scientists have begun to suspect that this intergalactic gas is probably a mixture of gases left over from the “big bang” when the galaxies were formed and gas was forced out of galaxies by supernova explosions
吗？
我感觉应该不是，因为这些科学家也是同意是有heavy rain fall in的，只是在猜想这些heavy rain的组成是啥，但是后文又说these strands were gases that had been blown out by an explosion in the galaxy.和那些科学家说的big bang时galaxies形成，gas被超新星挤出galaxies又是一样的。。。。

求解求解！！

不胜感激！！！

欢迎光临国际顶尖MBA申请交流平台--TOPWAY MBA (http://forum.topway.org/)