An Etymological Dictionary of Astronomy and Astrophysics

The → Zeeman effect when the emitting source is viewed in the direction of the magnetic field. In the normal longitudinal effect, each spectral line is split into two components with frequencies ν ± Δν. The line with the frequency ν - Δν shows left-hand → circular polarization and that with frequency
ν + Δν shows right-hand circular polarization. → transverse Zeeman effect.

See also: → longitudinal; → Zeeman effect.