supernova－－－天文类

If a supernova (the explosion of a massive star) triggered star formation from dense clouds of gas and dust, and if the most massive star to be formed from the cloud evolved into a supernova and triggered a new round of star formation, and so on, then a chain of star-forming regions would result. If many such chains were created in a differentially rotating galaxy, the distribution of stars would resemble the observed distribution in a spiral galaxy (spiral galaxy: n.(=spiral nebula)螺旋星云,旋涡星云).

This line of reasoning underlies an exciting new theory of spiral-galaxy structure. A computer simulation based on this theory has reproduced the appearance of many spiral galaxies without assuming an underlying density wave, the hallmark (a distinguishing characteristic, trait, or feature “the dramatic flourishes which are the hallmark of the trial lawyer Marion K. Sanders”) of the most widely accepted theory of the large-scale structure of spiral galaxies. That theory maintains that a density wave of spiral form sweeps through the central plane of a galaxy, compressing clouds of gas and dust, which collapse into stars that form a spiral pattern.

　　倘若一颗超新星（supernova，即一颗质量庞大的星星的爆炸）触发星星从稠密的气体和尘埃云中形成，且倘若从云层中形成的质量最庞大的星星演变成一颗超新星并触发新的一轮星星形成过程，如此循环下去的话，那么，一系列能形成星星的区域便告产生。倘若许多这样的系列在一个以不同的方式旋转着的星系中得以形成的话，那以，星星的分布将类似于所观察到的螺旋形星系（spiral galaxy）内的星星分布。这一推理思路构成了一种激动人心的有关螺旋形星系结构的新理论的基础。建立在这一理论基础上的一种计算机模拟研究再现了许多螺旋形星系的外观，在此过程中并不假设一基本密度波（density wave）的存在，而所谓的密度波则是那种最广为人们接受的有关大规模螺旋形星结构理论的标志特征。那种理论坚持认为，螺旋形状的密度波贯穿星系的中央层面，将气体和尘埃的云层压缩，这些云层则坍缩为一颗颗星星，形成一螺旋状结构。

 

 

http://www.taisha.org/bbs/thread-1586782-11-1.html