Fr.: raie aurorale
1) A prominent → forbidden line in the spectra of
the aurora at wavelengths of 5577 and 6300 Å giving the aurora its
characteristic green and red colors.
Both are emitted by atomic oxygen, the former in its transition from the
second lowest excited electronic state (1S) to the lowest
excited electronic state (1D), the latter in its transition
from the lowest excited electronic state (1D) to the atomic
ground state (3P).
Fr.: raie transaurorale
A forbidden line emitted by interstellar ionized gas by several atomic species (O, O+, O++, N+, S++, etc.) corresponding to the transition from the electronic state 1S to 3P. Examples are the ultraviolet line of the doubly ionized oxygen [O III] at 2321 A and [N II] 3063 A. → auroral line; → forbidden line; → nebular line.