Short ones are from merging neutron stars.

短的则来自合并的中子星。

Creating new elements and merging neutron stars used to be purely theoretical, but in recent years we've actually witnessed these collisions and felt their gravitational aftershocks.

创造新元素和合并中子星过去纯粹是理论上的，但近年来我们亲眼目睹了这些碰撞并感受到了它们的引力余震。