What is created when molecular clouds combine to form a solid mass?

When molecular clouds, which are dense regions within the interstellar medium composed mostly of gas and dust, combine, they can initiate the process of star formation. This process leads to the formation of a protostar. As the molecular clouds merge, gravitational forces cause the material to collapse inward, resulting in a concentration of mass that progressively heats up due to the increasing pressure in the core.

During this stage, the material is not yet undergoing nuclear fusion, which is a defining characteristic of a true star, but it is on its way to becoming one. Once the core temperature becomes sufficiently high, hydrogen fusion begins, marking the transition from protostar to main-sequence star. This process is essential in stellar evolution, as it sets the foundation for the birth of stars in various environments within the universe.

In contrast, a black hole does not result from the merger of molecular clouds but rather from the remnants of a massive star that has undergone supernova after exhausting its nuclear fuel. A neutron star also forms from a supernova explosion of a massive star and is not part of the initial stages of star formation from molecular clouds. Lastly, a red giant is a later stage in a star's life cycle, occurring after a star has exhausted hydrogen in its core