The evolution of a protostar slows significantly as it approaches the main sequence.

Question

Quizplus · Accepted Answer

As a protostar contracts and heats up, its evolution becomes more rapid until it reaches the main sequence, at which point it settles into a stable state and evolves more slowly over a much longer timescale. As a protostar collapses and heats up, it follows a path on the Hertzsprung-Russell diagram called the Hayashi track. When the protostar reaches a certain temperature and luminosity, it begins to fuse hydrogen in its core and becomes a true star on the main sequence. This process is called the zero-age main sequence. As the protostar approaches the main sequence, its contraction and heating slow down significantly, leading to a much slower evolution.

The Evolution of a Protostar Slows Significantly as It Approaches