Hydrogen is the most abundant element in the universe and constitutes the bulk of interstellar clouds, providing the raw material for star formation.

A protostar is a young star in its early stages of formation, before it has reached the main sequence and begun to fuse hydrogen in its core.

Gravitational force is the dominant force responsible for the collapse of interstellar clouds, causing the material to condense and form protostars.

A protostar disk is a rotating disk of gas and dust that surrounds a protostar, from which planets and other celestial bodies can form.

In the early stages of formation, protostars generate energy primarily through gravitational contraction, as the material falls inward and releases gravitational potential energy.

Emission nebulas are regions of ionized gas that emit their own light due to the presence of high-energy radiation from nearby stars.

Ignition refers to the process by which a protostar reaches the main sequence and begins to fuse hydrogen in its core, marking the start of its stable energy production.

The mass of a star is primarily determined by the mass of the initial cloud from which it forms.

Stellar wind refers to the continuous outflow of gas from the outer layers of a star, which can lead to significant mass loss over time.

Detached binaries are binary star systems in which the two stars are gravitationally bound but do not share a common envelope.

Neutron stars are the remnants of massive stars that have undergone a supernova explosion and are composed primarily of neutrons.

Open clusters are groups of young stars that are loosely bound together and typically contain fewer than 1000 stars.

Fragmentation refers to the process by which a molecular cloud breaks up into smaller clumps, each of which can potentially form a star.

O-type stars are massive, hot stars that form from the collapse of massive molecular clouds.

Magnetohydrodynamics is the study of the interaction between magnetic fields and electrically conducting fluids, which is relevant to understanding the behavior of stars and their surrounding environments.