Nebularis
Nebularis is a term used in speculative astronomy and in science fiction to describe a proposed class of extremely diffuse, large-scale interstellar gas clouds. The name derives from nebula, reflecting its cloud-like nature. In theoretical discussions, Nebularis are envisioned as vast, filamentary structures extending from tens to hundreds of light-years, with very low particle densities and predominantly atomic gas, often with subsolar metallicity. They are imagined as cold to moderately warm, stabilized by a balance of turbulence, magnetic fields, and weak self-gravity.
Observationally, Nebularis would be difficult to detect; they would produce faint 21 cm hydrogen emission and
Compared with known components such as diffuse ionized gas and high-velocity clouds, Nebularis remain unconfirmed as
The term reflects the Latin origin of nebula, emphasizing the cloud-like character of these hypothetical structures