An Etymological Dictionary of Astronomy and Astrophysics
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Of or pertaining to longitude or length. Extending in the direction of the length.

Adj. of → longitude.

1) A → magnetic field whose lines of force (→ line of force) run parallel to the long axis of the → magnet. Longitudinal magnetization of a component can be accomplished using the longitudinal field set up by a → coil or → solenoid. It can also be accomplished using permanent magnets or electromagnets.
2) In → stellar magnetic field observations, the magnetic field along the → line of sight.

→ longitudinal; → magnetic; → field.

In special relativity theory, the mass of a body when the acceleration is parallel or anti-parallel to velocity: m_l = m₀ / [1 - (v/c)²]^3/2, where m₀ is the → rest mass, v is the velocity, and c the → velocity of light. → transverse mass.

→ longitudinal; → mass.

A wave vibrating along the direction of propagation, such as a → sound wave. → transverse wave.

→ longitudinal; → wave.

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.

→ longitudinal; → Zeeman effect.