What is the general outcome for stars on the Hayashi Track as they become denser?

The Hayashi Track represents a crucial phase in the evolutionary path of young stars, particularly during the early stages of stellar formation when they are contracting and densifying. As stars evolve along the Hayashi Track on the Hertzsprung-Russell diagram, they become increasingly dense while still not yet igniting nuclear fusion in their cores.

During this contraction phase, the gravitational forces pulling the star inward lead to an increase in temperature and pressure in the core. However, the outer layers of the star remain relatively cool and expansive, resulting in a decrease in the overall luminosity. As the star becomes denser and approaches the necessary conditions for hydrogen fusion to commence, it continues to lose brightness. This pattern holds true until the temperatures and pressures in the core rise sufficiently to trigger nuclear fusion, at which point the star will shift out of the Hayashi Track and begin a new phase of stellar evolution.

Thus, the assertion that stars on the Hayashi Track become less luminous until fusion begins is consistent with the understanding of stellar development during this particular stage. The other outcomes, such as remaining at constant brightness or transforming into supernovae, do not accurately reflect the dynamics of star formation in this context.