所以如果不被压缩到很致密，这些大质量星云，比如有太阳质量100，000倍的California星云，则不一定会形成新生恒星和行星。

So, by not collapsing into denser regions, these massive nebulae, like the 100,000 solar mass California Nebula shown above, don't necessarily start making baby stars and planets.

youdao

在星云里面，某些部分足够致密而在自身重力影响下开始塌缩。

Within the cloud, some parts are sufficiently dense to start collapsing under their own gravity.

youdao

画面中央偏下，也就是位在参宿一右方的马头星云，由致密的黑暗尘埃组成，应当是天空中最被认可的形状。

Below the frame center and just to the right of Alnitak lies the Horsehead nebula, a dark indentation of dense dust that has perhaps the most recognized nebular shapes on the sky.

youdao