As our nebula began to collapse under its own gravity and spin faster, a dense clump of matter formed in the center. It's called a protostar.

当星云在自身重力作用下崩溃和更加快速地旋转时，星云中心成了集物质块。这叫做原恒星。

As described above, the collapse of a rotating cloud of gas and dust leads to the formation of an accretion disk through which matter is channeled onto a central protostar.

部分重力能量在崩溃过程中会以红外式损失掉，其馀则会用于增加天体核心温度。