An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

A → software → utility that enables a → user to view each of the tasks currently running on the → computer, each of the → processes, and the overall performance of the computer.

→ task; → manager.

In a rapidly rotating fluid, the fluid velocity is constant along any line parallel to the axis of rotation.

→ Taylor number; Joseph Proudman (1888-1975), British mathematician and oceanographer.

The → Zeeman effect when observed at right angles to the orientation of the magnetic field. Un un-displaced line is observed along with a doublet, three lines in all, with the frequencies ν and ν ± Δν. The two displaced components correspond to a plane of → polarization parallel to the external magnetic field and the un-displaced line to a plane of polarization perpendicular to this field. → longitudinal Zeeman effect.

→ transverse; → Zeeman effect.

The upper part of the Earth's → mantle which begins at the base of the → crust around 35 km and extends downward to about 410 km.

→ upper; → mantle.

For all metals the ratio of the → thermal conductivity, κ, to the → electrical conductivity, σ, is directly proportional to the absolute temperature: K/σ = (1/3)(πk/e)²T, where k is → Boltzmann's constant and e the electron's charge.

Named after the German physicists Gustav Heinrich Wiedemann (1826-1899) and Rudolph Franz (1826-1902); → law.

The → female human being.

M.E. womman, wimman, O.E. wifman, from wif "female" + man "human being."

Zan "woman, wife" (variants Baluci, Zâzâ jan, Gorgâni cen, Baxtiyâri zine, Sangesari, Tâti, Kurd. žen, Kurd. kenâ, Karingâni yan); Mid.Pers. zan "woman, wife;" kaniz "maid, virgin, girl;" Av. jəni- "woman, wife;" cf. Skt. jáni- "woman, wife;" Gk. gyne "woman, wife;" O.E. cwen "queen, woman, wife" (E. queen; Arm. kin "woman;" PIE base *g^wenh- "woman, wife."

The splitting of spectral lines into closely-spaced components when the radiating substance is placed in a strong → magnetic field. Distinction is made between the normal and → anomalous Zeeman effects, and also the longitudinal and transverse Zeeman effects. In the normal → longitudinal Zeeman effect each spectral line is split into two components with frequencies ν ± Δν. In the normal → transverse Zeeman effect un un-displaced line is observed along with a doublet, i.e. three lines in all, with the frequencies ν and ν ±Δν. In the classical theory of the normal Zeeman effect, the motion of an electron in an atom is regarded as the harmonic oscillation of a linear harmonic oscillator. Arbitrary linearly polarized oscillation of the electron can be resolved into two oscillations: one along the magnetic field and the other in a plane perpendicular to this field. The latter can be further resolved into two oscillations, circularly polarized with opposite directions of rotation that occur in the Larmor precession frequency. Classical theory cannot explain the anomalous Zeeman effect. Both effects are accounted for in quantum mechanics as the result of changes in the energy levels of atomic electrons due to the interaction of their → orbital angular momentum and → spin angular momentum with each other and with the external magnetic field. See also → inverse Zeeman effect.

Named after Pieter Zeeman (1865-1943), Dutch physicist who discovered the phenomenon; → effect.