2015-01-30 BBC:星光七纪元-5

Many regions within these clouds can stay like that for ever for millions of years until something happens, a trigger and then a star forms.The trigger for such a monumental event doesn't have to be much, two clouds conbine as they pass, or a distant cosmic event can send a shockwave, just something to give the cloud a squeeze.

All you need is a little bit of pressure to allow the gas to be dense¹ enough for gravity to take over and collapse² to start.

The particles of dust and gas that had been quietly floating in space now start being pulled together, gravitational attraction draws them towards each other, faster and faster.

As the collapse continue to happen, the gas and the dust will fall into the center and they will become denser³ and denser, and the center of the cloud will become hotter and hotter.

The laws of nature mean that when matter gets compressed, it heats up, over millions of years, the protostar grows, increasing the pressure and heat in its core, until finally it reaches a critical temperature.

About 15 million degrees and a fundamental process will start in the core of the embryonic⁴ star.

Almost in a flash, the core of the star like our own sun's once did dazzlingly lights up.

1 dense   

a.密集的，稠密的，浓密的；密度大的

参考例句：

• The general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。
• The path was completely covered by the dense foliage. 小路被树叶厚厚地盖了一层。

2 collapse   

vi.累倒；昏倒；倒塌；塌陷

参考例句：

• The country's economy is on the verge of collapse.国家的经济已到了崩溃的边缘。
• The engineer made a complete diagnosis of the bridge's collapse.工程师对桥的倒塌做了一次彻底的调查分析。

3 denser   

adj. 不易看透的, 密集的, 浓厚的, 愚钝的

参考例句：

• The denser population necessitates closer consolidation both for internal and external action. 住得日益稠密的居民，对内和对外都不得不更紧密地团结起来。 来自英汉非文学 - 家庭、私有制和国家的起源
• As Tito entered the neighbourhood of San Martino, he found the throng rather denser. 蒂托走近圣马丁教堂附近一带时，发现人群相当密集。

4 embryonic   

adj.胚胎的

参考例句：

• It is still in an embryonic stage.它还处于萌芽阶段。
• The plan,as yet,only exists in embryonic form.这个计划迄今为止还只是在酝酿之中。