# An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

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 equation of state   هموگش ِ حالت   hamugeš-e hâlatFr.: équation d'état   In physics and thermodynamics, the equation that describes the relationship between pressure, density, and temperature, e.g. → ideal gas law, → van der Waals equation, → polytropic process, → virial equation of state.→ equation; → state. equation of state parameter   پارامون ِ هموگش ِ حالت   pârâmun-e hamugeš-e hâlatFr.: paramètre de l'équation d'état   In cosmology, a → dimensionless parameter introduced by the → equation of state representing the ratio of the pressure to the energy density of a fluid, such as the → dark energy: w = p/ρ. The → deceleration or → acceleration of an → expanding Universe depends on this parameter (→ accelerating Universe). A number of numerical values of this parameter are as follows: for the → cosmological constant: w = -1, for → non-relativistic matter (present-day → baryons): w = 0, and for → relativistic matter (photons, neutrinos): w = +1/3. Together with Ω(dark energy) and Ω(matter), w provides a three-parameter description of the dark energy. The simplest parametrization of the dark energy is w = constant, although w might depend on → redshift.→ equation; → state; → parameter. equation of the equinoxes   هموگش ِ هموگانها   hamugeš-e hamugânhâFr.: équation des équinoxes   The difference between → apparent sidereal time and → mean sidereal time. It is due to the nutation of the Earth's polar axis of rotation about its precessional motion. It ranges from +0.8 to +1.2 seconds. Also known as → nutation in right ascension.→ equation; → equinox. equation of time   هموگش ِ زمان   hamugeš-e zamânFr.: équation du temps   The difference, due to Earth's elliptical orbit and variable orbital velocity, between apparent solar time and mean solar time. It varies throughout the year, and slightly from year to year. At present, it reaches extremes of about -14 minutes in February, and about +16 minutes in November. The equation of time is visually illustrated by an → analemma.→ equation; → time. equilibrium partitioning   پرکه‌بندی ِ ترازمند   parkebandi-ye tarâzmandFr.: équilibre de partition   A concept whereby chemical → concentrations among geological or environmental media are at equilibrium, and therefore the partitioning of metals in those media can be predicted based on → partition ratios. equilibrium position   نهش ِ ترازمندی   naheš-e tarâzmandi (#)Fr.: position d'équilibre   The position of an oscillating body at which no net force acts on it.→ equilibrium; → position. equipartition of energy   هموگپرکش ِ کاروژ   hamugparkeš-e kâružFr.: équipartition de l'énergie   1) General: Equal sharing of the → total energy among all → components of a → system. 2) In the → kinetic theory of gases, the → theorem according to which → molecules in → thermal equilibrium have the same average energy (1/2 kT) associated with each independent → degree of freedom of their motion.→ equi-; → partition. equivalent positions   نهش‌های ِ هموگ‌ارز   nehešhâ-ye hamug-arzFr.:   Complete set of points in any given space group which are obtained by performing the symmetry operations of the space group on a single point (x, y, z).→ equivalent; → position. ergonomics   ورزداتیک   varzdâtikFr.: ergonomie   The study of the relationship between people and their working environment, in particular its effect on a person's efficiency. Ergonomics is applied in designing equipment and office systems to maximize productivity by reducing discomfort and fatigue of people in their workplace.From Gk. ergon "work," → erg, + -nomics, → -nomy, → -ics.Varzdâtik, from varz "work, " cognate with Gk. ergon, → erg, + dâtik "law, rule," → -nomy. erosion   فرسایش   farsâyeš (#)Fr.: érosion   Geology: The act or state of eroding; state of being eroded. A general term applied to the wearing away and movement of earth materials by the action of water, glaciers, winds, gravity, etc.From M.Fr. erosion, from L. erosionem (nom. erosio), from erodere "to gnaw away," from → ex- "away" + rodere "to gnaw, eat away" (cf. Fr. and E. animal rat).Farsâyeš, from far- intensive prefix "much, abundant" (Mid.Pers. fra- "forward, before; much; around;" O.Pers. fra- "forward, forth;" Av. frā, fərā-, fra- "forward, forth; excessive;" cf. Skt. prá- "before; forward, in fron;" Gk. pro "before, in front of;" L. pro "on behalf of, in place of, before, for;" PIE *pro-) + verbal noun of sâyidan, variants sâbidan "to bruise, file," pasâvidan "to touch;" Khotanese sauy- "to rub;" Sogdian ps'w- "to touch;" Proto-Iranian *sau- "to rub." eruption   اسدرش   osdarešFr.: éruption   1) An act, process, or instance of erupting; something that is erupted or ejected. 2) → flare. 3) Geology: The ejection of molten rock, steam, etc., as from a volcano or geyser.Verbal noun of → erupt. ESPaDOnS      ESPaDOnSFr.: ESPaDOnS   An advanced stellar → spectropolarimeter designed and built at the Observatoire Midi-Pyréenées and installed at the → Canada-France-Hawaii Telescope (CFHT). It can obtain a a complete optical spectrum, from 370 nm to 1050 nm, in a single exposure. Among its characteristics: resolving power 65 000 to 80 000; 12% peak throughput (telescope and detector included); continuum subtracted linear and circular polarization spectra of the stellar light (in polarimetric mode). ESPaDOnS is used to study a broad range of important problems in stellar physics: from → stellar magnetic fields to → accretion disks and → extrasolar planets; from inhomogeneities and differential rotation on stellar surfaces to activity cycles and magnetic braking; from microscopic diffusion to turbulence, convection, and circulation in stellar interiors; from abundances and pulsations in stellar atmospheres to stellar winds; from the early phases of stellar formation to the late stages of stellar evolution; from extended circumstellar environments to distant interstellar medium (Donati et al., 2006, Solar Polarization, ASP Conf. Series, 358, 362, eds. R. Casini, B. W. Lites).Short for Echelle Spectro-Polarimetric Device for the O bservation of Stars; → echelle; → spectro-; → polarimetric; → device; → observation; → star. estimation   بر‌آوری   barâvari (#)Fr.: estimation   Statistics: The process by which sample data are used to indicate the value of an unknown quantity in a population.Verbal noun of → estimate. ethnoastronomy   قوم‌اخترشناسی   qowm-axtarshenâsiFr.: ethnologie   The study of the beliefs, interpretations, and practices of specific cultures regarding celestial objects or phenomena. Ethnoastronomy uses the tools and methodologies of → ethnology in the study of astronomical conceptions.→ ethno-; → astronomy. Euclidean division   بخش ِ اقلیدوسی   baxš-e OqlidosiFr.: division euclidienne   In arithmetic, the conventional process of division of two → integers. For a → real number a divided by b > 0, there exists a unique integer q and a real number r, 0 ≤ r