What are stellar nurseries primarily composed of?

Stellar nurseries, also known as star-forming regions or molecular clouds, are primarily composed of hydrogen molecules. These regions contain dense concentrations of gas and dust, with hydrogen being the most abundant element in the universe. In these environments, the density of hydrogen molecules allows for the gravitational collapse necessary to form new stars.

As regions of the nebula cool and compress, hydrogen molecules can interact to create the conditions for star formation. Once the gravitational forces are strong enough, hydrogen atoms begin to fuse, resulting in the birth of new stars. This molecular hydrogen is crucial not only as the primary fuel for star formation but also as a building block for the complex processes leading to the creation of various celestial bodies, including planets and other stellar structures.

Other elements such as carbon, helium, plasma, and oxygen do exist in the universe and within various astronomical structures, but they are not the primary constituents of stellar nurseries. The focus on hydrogen underscores its fundamental role in the lifecycle of stars and the universe's evolution.