What is a protostar?

A protostar is a stage in the lifecycle of a star where it is still in the process of forming. It is formed from the gravitational collapse of a giant molecular cloud composed of gas and dust. As the gas and dust in the cloud gather together due to gravity, a dense core is created at the center, which eventually becomes a protostar.

Protostar Formation

During the protostar stage, the temperature and pressure at the core of the star increase as more material accretes onto it. This increase in temperature and pressure eventually triggers nuclear fusion, the process through which a star generates energy by converting hydrogen into helium at its core.

Protostar Characteristics

A protostar is considered a pre-main sequence star, meaning it has not yet reached the stable phase of its lifecycle known as the main sequence. Protostars are often surrounded by a protoplanetary disk made up of gas and dust, from which planets may eventually form.

Stellar Evolution

As a protostar continues to accrete mass and undergo nuclear fusion, it evolves into a main sequence star, where it will spend the majority of its lifecycle. Stellar evolution describes the changes in a star's properties as it progresses through different stages from protostar to main sequence to the eventual end of its lifecycle as a white dwarf, neutron star, or black hole.