An Etymological Dictionary of Astronomy and Astrophysics
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Of or relating to or resembling a → nebula.

→ nebula + → -ar.

The part of a nebular object's → spectrum that is created by → free-free emission.

→ nebular; → continuum.

The hypothesis first put forward in the 18-th century that the solar system formed from a primeval nebula around the Sun. Same as the → Kant-Laplace hypothesis.

→ nebular; → hypothesis.

A → forbidden line that is found in the spectra of → interstellar  → ionized gas. The nebular lines are emitted by several atomic species (e.g. O, O⁺, O⁺⁺, N⁺, S⁺⁺) and correspond to the → transition from the electronic → metastable state ¹D to the → ground state  ³P. Examples are the doubly ionized oxygen lines [O III] at 4959 and 5007 Å (→ [O III] doublet) and the ionized nitrogen doublet [N II] at 6548 and 6583 Å. See also → auroral line; → transauroral line.

→ nebular; → line.

A type of eruptive variable star, mainly young FU Orionis and T Tauri types, associated with nebulosity.

→ nebular; → variable.