What process generates significant heat within a protostar before nuclear fusion ignites?

Answer

Gravitational contraction

The infall of matter onto the central mass generates enormous heat. Even though fusion has not started, the core becomes incredibly hot due to gravitational contraction during the protostar phase.

What process generates significant heat within a protostar before nuclear fusion ignites?

#Videos

Where Do Stars Come From? 4K - YouTube

How Did we Get Here? The Origin of Stars and Planets with Joan ...

SpaceOriginstars