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

The force that takes part in an → electroweak interaction.

→ electroweak; → force.

The unified description of two of the four fundamental interactions of nature, → electromagnetism and the → weak interaction which would merge into a single force under conditions of extreme temperature (above 10¹⁶ degrees, 10² GeV) prevalent in the early history of the → Universe.

→ electroweak; → interaction.

A postulated type of star that could form toward the end of a → massive star's life, after → nuclear fusion has stopped in its → core, and before the star → collapses into a → black hole. In those → extreme conditions, when → temperature and → density inside the star are very high, → quarks could convert into → leptons. Hence huge amounts of energy can be released, much of which would be in the form of → neutrinos.

→ electroweak; → star.

Elegance quality; something elegant.

Noun from → elegant.

Gracefully refined and dignified, as in tastes, habits, or literary style; graceful in form or movement; excellent; fine; superior (Dictionary.com).

M.E., from M.Fr., from L. elegantem (nominative elegans) "choice, fine, tasteful," from eligere "to select, choose."

Qašang "elegant, nicely fitted up" (Steingass), variant šang; cf. Sogd. xšang "beautiful, magnificient, excellent," maybe related to Av. xšnu- "to entertain, welcome, take care of (a guest)," O.Pers. xšnu- "to be satisfied, glad," Pers. xošnud "satisfied, content."

An equation with surprising simplicity that expresses a fundamental result relating several apparently unassociable elements. For example, → Euler's formula for the particular case of θ = π, and the → mass-energy relation.

→ elegant; → equation.

1) General: A component or constituent of a whole or one of the parts into which a whole may be resolved by analysis.
2) Astro.: Any of the data required to define the precise nature of an orbit and to determine the position of a planet in the orbit at any given time. → orbital element.
3) Chemistry:: One of the 117 presently known substances that cannot be decomposed by chemical reaction into a simpler substance.
4) Math.:a) Of a cylinder or cone, the generating line of the surface, taken in any position. b) Of a set, any member of the set.

From O.Fr. élément, from L. elementum "rudiment, one of the four elements, first principle," origin unknown.

Bonpâr, from bon "basis; root; foundation; bottom;" Mid.Pers. bun "root; foundation; beginning," Av. būna- "base, depth," cf. Skt. bundha-, budhná- "base, bottom," Pali bunda- "root of tree" + pâr contraction of pâré "piece, part, portion, fragment;" Mid.Pers. pârag "piece, part, portion; gift, offering, bribe;" Av. pāra- "debt," from par- "to remunerate, equalize; to condemn;" PIE *per- "to sell, hand over, distribute; to assign;" cf. L. pars "part, piece, side, share," portio "share, portion;" Gk. peprotai "it has been granted;" Skt. purti- "reward;" Hitt. pars-, parsiya- "to break, crumble." Onsor from Ar.

An important physical process occurring in stars, which is the relative separation of the various → chemical elements. It is caused by → gravitational settling and → thermal diffusion, on the one hand, and → radiative levitation on the other. This process, which was described by Michaud (1970) to account for the abundance anomalies observed in → chemically peculiar  → A star, is now recognized as occuring in all types of stars. Its influence on the observed → chemical abundances is extremely variable, however, due to competing macroscopic motions like → convective  → mixing or rotation-induced → turbulence. In the Sun, no observable abundance anomalies are expected from element diffusion, as the time scale of the process is longer than the solar lifetime. However the small induced → depletion of → helium and → heavy elements by about 20% is detectable through → helioseismology. Such detections are more difficult in stars, as only global → oscillation modes can be detected, in contrast to the Sun, where local oscillations of the surface can be analyzed (Théado et al., 2005, A&A 437, 553).

→ element; → diffusion.

Emission nebulae: The relative amount of a given → chemical element in an ionized nebula with respect to another element, usually → hydrogen. Elemental abundance ratios of → emission nebulae are obtained either by adding the observed → ionic abundances of the element or by using → ionization correction factors. Same as → total abundance.

Elemental, from M.L. elementalis, → element + -al; abundance, from O.Fr. abundance, from L. abundantia "fullness," from abundare "to overflow," from L. ab- "away" + undare "to surge," from unda "water, wave;" → abundance.

A particle which cannot be divided into other constituents. More specifically, a particle whose field appears in the fundamental field equations of the unified field theory of elementary particles, in particular in the Lagrangian. For example, the → electron, the → photon, and the → quark are elementary particles, whereas the proton and neutron are not. The elementary nature of a particle can be revised depending on new observations or theories. Also called → fundamental particle.

Elementary, M.E. elementare, from M.F. élémentaire, from L. elementarius, from → element + adj. suffix -arius; → particle.

Bonyâdin, from bonyâd "basis, foundation," variant of bonlâd, from bon "basis; root; foundation; bottom" → element + lâd "root; foundation; reason, cause; wall" + adj. suffix -in.

The time required for → light to cross the classical radius of the electron (→ electron radius): t_e = r_e/c ≅ 10^-23 s.

→ elementary particle; → time.

→ orbital element.

→ element; → orbit.

An elongated structure of → interstellar dust and gas which absorbs the radiation from background stars in an → H II region. These structures are the denser remnants of → molecular clouds from which → massive stars are formed. Elephant trunks are eventually dissipated by the action of the → ionizing radiation and → stellar wind of the associated massive stars. A remarkable example of these structures is displayed by the → HST image of the → Eagle Nebula as → pillars of obscuring matter protruding from the interior wall of a dark molecular cloud. Some → Bok globules may represent the remaining densest fragments of elephant trunks.

M.E. elephant, from O.Fr. olifant, from L. elephantus, from Gk. elephas "elephant, ivory," probably from a non-I.E. language, likely via Phoenician; trunk, from M.E. trunke, O.Fr. tronc, from L. truncus "stem, trunk, stump."

Xortum "the proboscis of an elephant," loanword from Ar. xartum; fil, pil "elephant," from Mid.Pers. pil "elephant;" O.Pers. piru- "ivory."

An elongated dark structure of gas and dust in the → H II region IC 1396. It spans about 5 degrees on the sky in the constellation → Cepheus, about 2400 → light-years from the Earth. The Elephant Trunk Nebula is believed to be site of star formation, containing several very young stars. It is an example of → elephant trunks associated with star forming regions.

→ elephant trunk; → nebula.

1) To move or raise to a higher place or position; lift up.
2) To raise to a higher state, rank, or office; exalt; promote (Dictionary.com).

From L. elevatus, p.p. of elevare "to lift up, raise," from → ex- "out" + levare "lighten, raise," from levis "light" in weight, → lever.

Bâlâyidan, from bâla "up, above, high, elevated, height," related to boland "high," borz, "height, → magnitude."

The floor below a telescope used to lift observers to the level of the telescope's eyepiece, since the telescope is tilted at varying angles when it is in use.

Elevating, adj. of → elevate; → floor.

1) The height to which something is elevated or to which it rises.
2) An elevated place, thing, or part; an eminence (Dictionary.com).

Verbal noun of → elevate; → -tion.

A → chemical reaction on solid surfaces in which one atom or molecule is → adsorbed on the catalyst surface, and another reacts directly from the gas phase. This type of mechanism may occur preferentially on very small → dust grains, where transient heating events prevent weakly bound species from remaining and in larger grains at high temperatures. Compare with the → Langmuir-Hinshelwood mechanism.

Proposed in 1938 by D. D. Eley (1914-2015), a British chemist and Professor of Physical Chemistry and E. K. Rideal (1890-1974), an English physical chemist.

1) To remove or get rid of, especially as being in some way undesirable.
2) Math.: To remove (an unknown variable) from two or more simultaneous equations (Dictionary.com).

L. eliminatus, p.p. of eliminare "to thrust out of doors, expel," from ex limine "off the threshold," from → ex- "off, out" + limine, ablative of limen "threshold."

Osândan, from Tabari uzitan, huzənniyən, hozənniyan "to expel," from os- "out," → ex-, + -ândan suffix of transitive verbs.

1) The act of eliminating; the state of being eliminated.
Math.: The process of solving a system of simultaneous → equations by using various techniques to remove the → variables successively (Dictionary.com).

Verbal noun of → eliminate; → -tion.