hydrogenoids

Hydrogenoids are theoretical celestial objects consisting predominantly of hydrogen, the simplest and most abundant element in the universe. They are sometimes conceptualized in astrophysics as primitive or early-stage stars, or as remnants of cosmic structures primarily composed of hydrogen gas. Unlike conventional stars, which generate energy through nuclear fusion of heavier elements, hydrogenoids are generally characterized by their reliance on gravitational contraction or other processes for their energy output, if any.

The term "hydrogenoid" can also refer to certain types of artificial or simulated models used in astrophysical research to understand the behavior of hydrogen under various conditions. In the context of planetary science, it may describe planets or exoplanets with atmospheres or compositions dominated by hydrogen, especially gas giants like Jupiter and Saturn, although these are more accurately termed "hydrogen-rich planets" rather than hydrogenoids.

In theoretical models, hydrogenoids might represent primitive stellar objects or substellar bodies that have not yet ignited nuclear fusion or have cooled down after stellar death, leaving behind hydrogen-dominated atmospheres or shells. They are of interest in studies concerning the early universe, star formation, and the evolution of cosmic structures.

Overall, hydrogenoids remain a largely hypothetical or conceptual category within astrophysics, primarily serving as models or representations in scientific research. Their study contributes to understanding the formation, evolution, and diversity of celestial bodies composed mainly of hydrogen, the fundamental building block of the universe.