Protostjernefasen

Protostjernefasen, also known as the protostar phase, is the initial stage in the formation of a star. This phase begins when a dense core within a molecular cloud, known as a Bok globule, collapses under its own gravity. The collapse is triggered by the cloud's internal turbulence or the shockwave from a nearby supernova.

During this phase, the collapsing material heats up due to the conversion of gravitational potential energy into thermal energy. This heating causes the core to become opaque to its own radiation, leading to a rapid increase in temperature and pressure. The protostar is not yet hot enough to initiate nuclear fusion, so it is not yet a true star.

The protostar phase can last for several hundred thousand to a few million years, depending on the mass of the forming star. As the protostar continues to accrete mass from the surrounding cloud, it grows in size and luminosity. Eventually, the core becomes hot and dense enough to begin nuclear fusion, marking the transition to the main sequence phase of stellar evolution.

The protostar phase is a crucial stage in the life of a star, as it sets the initial conditions for the star's future evolution. The mass and composition of the protostar will determine its final fate, whether it will become a low-mass star like our Sun, a high-mass star that ends its life in a supernova, or an intermediate-mass star that becomes a white dwarf.