An Etymological Dictionary of Astronomy and Astrophysics
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Any of up to seven energy levels on which an electron may exist within an atom, the energies of the electrons on the same level being equal and on different levels being unequal. The number of electrons permitted in a shell is equal to 2n². A shell contains n² orbitals, and n subshells.

→ electron; → shell.

1) The temperature of electrons in an interstellar ionized nebula (e.g. in → H II regions and → planetary nebulae) as determined by characteristic → emission lines (optical → forbidden lines or → radio recombination lines).
2) In the → solar wind, the temperature derived from the mean → thermal agitation of the electrons. More specifically, electric field receivers on board space probes carry out the spectroscopy of the → thermal noise due to the potential fluctuations produced by the thermal agitation of the electrons, yielding the electron temperature in certain conditions (N. Meyer-Vernet, 2007, Basics of the Solar Wind, Cambridge Univ. Press). See also → proton temperature.

→ electron; → temperature.

→ electron-volt.

→ electron; → volt.

The simultaneous formation of an → electron and a → positron in the → pair production process.

→ electron; → positron; → pair.

A → line broadening phenomenon involving the scattering effect of → free electrons on the → radiation transfer in → stellar atmospheres. The scattering of radiation by free electrons plays an important role in the atmospheres of → hot stars, such as → O-types, early → B-types, and → Wolf-Rayet stars. The first detailed study of electron scattering in Wolf-Rayet stars was by Castor et al. (1970), who used electron scattering to explain the broad emission wings of N IV λ3483 in HD 192163. In → P Cygni stars the explanation of the very extended (almost symmetric) wings on the → Balmer lines as caused by electron scattering was first made by Bernat & Lambert (1978). Hillier (1991) showed that significant reduction in the strength of an electron-scattering wing can be achieved in a model of → clumped wind for a lower mean → mass loss rate. This resulted in a better agreement between observations and theoretical predictions. Electron-scattering wings provide diagnostics regarding the presence of density inhomogeneities in → stellar winds (Münch, 1948, ApJ 108, 116; Hillier, 1991, A&A 247, 455).

→ electron; → scattering; → wing.

The energy acquired by an electron when accelerated through a → potential difference of 1 volt (1 eV = 1.602 × 10^-12 → ergs = 11605 → kelvins).

→ electron; → volt.

1) Of or relating to electrons or to an electron.
2) Of or relating to → electronics or to → devices, → circuits, or systems developed through electronics (Dictionary.com).

→ electron; → -ic.

In molecular quantum mechanics, any of → quantum states corresponding to a particular → electron configuration (i.e. an arrangement of the electron(s) in certain → orbitals). The electron configuration with the lowest energy is called the → ground state. All higher energy states are called → excited states.

→ electronic; → state.

The → transfer of an → electron from one → energy level to another.

→ electronic; → transition.

The science dealing with the development and application of → devices and → systems involving the flow of → electrons in a → vacuum, in → gaseous media, and in → semiconductors (Dictionary.com).

→ electron; → -ics.

An instrument for detecting electric charges or → potential differences.

→ electro-; → -scope.

Referring to electric charges at rest.

→ electro-; → static.

A quantity of electricity at rest on the surface of an insulator or an insulated conductor.

→ electrostatic; → charge.

A region of space in which a non-moving → electric charge would be subjected to a force of attraction or repulsion as a result of the presence of another stationary electric charge. The electrostatic field is a special case of the → electromagnetic field.

→ electrostatic; → field.

The production of stationary electric charges on an uncharged object as a result of a charged body being brought near it without touching it. A positive charge will induce a negative charge, and vice versa.

→ electrostatic; → induction.

The unit of electric charge in the → cgs system of units. Also called the → statcoulomb. The esu is defined such that if two objects, each carrying a charge of +1 esu, are 1 cm aparat, then they repel each other with a force of 1 → dyne. 1 esu = 3.3356 × 10^-10 → coulombs.

→ electrostatic; → unit; → charge.

In a → plasma, a disturbance that is devoid of magnetic field, and hence can be expressed by an electrostatic potential. The electric field is always parallel to the propagation vector, so that the electrostatic wave is → longitudinal.

→ electrostatic; → wave.

The branch of → electricity dealing with the phenomena and properties of stationary → electric charges, as opposed to → electrodynamics. It involves the build-up of charge on the → surface of → objects due to → contact with other surfaces.

→ electro- + → statics.

Of, relating to, or being the → unification of → electromagnetism and the → weak interaction.

→ electro-; → weak.

A period in the early history of the Universe lasting from 10^-36 to 10^-12 seconds after the → Big Bang. The electroweak epoch begins at the same time as cosmic → inflation is triggered. This is also the time when the → strong force breaks from the → grand unified force and ends with another → phase transition will occur in which the → weak interaction breaks from the → electroweak force.

→ electroweak; → epoch.