An Etymological Dictionary of Astronomy and Astrophysics
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A magnetic field whose lines of force are oriented along a particular direction or by a particular manner (axially, vertically; randomly, properly, etc.)

→ aligned; → magnetic field.

A property possessed by some → metals, → alloys, and salts of transition elements in which there is a lack of → magnetic moment due to the antiparallel or spiral arrangement of atomic → magnetic moments.

→ anti- + → ferromagnetism.

In the → solar dynamo model, a magnetic field that points from east to west or vice-versa.

→ azimuthal; → magnetic; → field.

A fundamental constant, first calculated by Bohr, for the intrinsic → spin magnetic moment of the electron. It is given by: μ_B = eħ/2m_e = 9.27 x 10^-24 joule/tesla = 5.79 x 10^-5 eV/tesla, representing the minimum amount of magnetism which can be caused by the revolution of an electron around an atomic nucleus. It serves as a unit for measuring the magnetic moments of atomic particles.

→ Bohr; magneton, from → magnet + → -on.

A → magnetic field whose lines of force (→ line of force) run around the perimeter of the magnet.

→ circular; → magnetic; → field.

Relative to or characterized by → diamagnetism.

→ diamagnetism.

The property of a substance, like bismuth, that creates a weak magnetic field in opposition of an externally applied magnetic field, thus causing a repulsive effect. In diamagnetic materials the → magnetic moments of individual atoms are not permanent. Within each atom the electron spins and orbital motions all exactly balance out, so any particular atom has no net magnetic moment. The external magnetic field generates little currents by induction. According to → Lenz's law, the induced magnetic moments of the atoms are directed opposite to the magnetic field.

Diamagnetic, from Gk. dia- a prefix used with several meanings "passing through; thoroughly; completely; going apart," and in the present case "opposed;" → magnetic. magnetic.

Pâdmeqnât, from pâd- "against, contrary," → anti-, + megnât→ magnetism.

A → magnetic field produced by a system possessing a net magnetic → dipole moment.

→ dipolar; → magnetic; → field.

A temporary magnet made by coiling wire around an → iron core. When current flows in the coil, or → solenoid, the iron becomes a → magnet. The electromagnet acts as a magnet only so long as the current is flowing in the solenoid.

→ electro-; → magnet.

Of or pertaining to electromagnetism or electromagnetic fields.

→ electro- + → magnetic

An → electromagnetic signal associated with the location on the sky and the time of a → gravitational wave event. The electromagnetic signal is predicted by models to be associated with the → merger of a → compact binary star system composed of two → neutron stars (NS) or a neutron star and a → black hole (BH). Accordingly, the gravitational waves are accompanied by a short-duration → gamma-ray burst (GRB) powered by the → accretion of material that remains in a → centrifugally supported → torus around the BH following the merger. NS-NS/BH-NS mergers are also predicted to be accompanied by a more isotropic counterpart, commonly known as a → kilonova. Kilonovae are day to week-long thermal, → supernova-like → transients, and are powered by the → radioactive decay of heavy, neutron-rich elements synthesized by the → r-process in the expanding merger ejecta (Li and Paczynski 1998). The first detection of an electromagnetic counterpart to gravitational waves belongs to → GW170817.

→ electromagnetic; → counterpart.

Same as → fine-structure constant.

→ electromagnetic; → coupling; → constant.

A region of space consisting of coupled electric and magnetic lines of force at each point, generated by time-varying currents and accelerated charges.

→ electromagnetic; → field.

The fundamental force that is associated with electric and magnetic fields. One of the four fundamental forces of nature, it is carried by photons.

→ electromagnetic; → force.

The production of an → electromotive force in a circuit caused by a variation in the magnetic flux through the circuit. If this variation is produced by a change in the current flowing in the circuit itself, it is called → self-induction. If due to the variation in a current in some other circuit, it is called mutual induction. See also → Faraday's law of induction.

→ electromagnetic; → induction.

The combination of both → electric scalar potential and → magnetic vector potential.

→ electromagnetic; → potential.

Radiation propagating in the form of an advancing wave in electric and magnetic fields. It includes radio waves, infrared, visible light, ultraviolet, X-rays, and gamma rays.

→ electromagnetic; → radiation.

Information transmitted by means of a modulated current or an electromagnetic wave and received by telephone, radio, television, etc.

→ electromagnetic; → signal.

The range of frequencies over which electromagnetic waves are propagated. → electromagnetic radiation.

→ electromagnetic; → spectrum.

The description of combined electric and magnetic fields mainly by → Maxwell's equations. Same as → electromagnetism.

→ electromagnetic; → theory.