Of or relating to or resembling a → nebula.
Fr.: continuum nébulaire
The part of a nebular object's → spectrum that is created by → free-free emission.
Fr.: hypothèse nébulaire
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.
Fr.: raie nébulaire
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.
Fr.: variable nébulaire
A type of eruptive variable star, mainly young FU Orionis and T Tauri types, associated with nebulosity.