A typical protostar may be several thousand times more luminous than the Sun. What is thesource of this energy?

Question

Quizplus · Accepted Answer

The energy of a protostar comes from the release of gravitational energy as the protostar continues to shrink. As it becomes denser and hotter, the pressure and temperature in its core increase until they are high enough to initiate nuclear fusion, which is what powers the star for the majority of its lifetime. However, during the earlier stage of protostar formation, it is the release of gravitational energy that provides the bulk of the energy. The source of energy in a protostar is the release of gravitational energy as it continues to shrink. As the protostar collapses under its own gravity, the gas heats up and the release of gravitational potential energy causes the temperature and luminosity to increase. This process continues until the core temperature is high enough to ignite nuclear fusion, at which point the protostar becomes a main sequence star.

A Typical Protostar May Be Several Thousand Times More Luminous