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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 128 Search : art
proto-Earth
  پوروا-زمین   
purvâ-Zamin

Fr.: proto-Terre   

The planet Earth during its → protoplanetary stage.

proto-; → Earth.

quarter
  چارَک   
cârak (#)

Fr.: quartier   

A fourth of the Moon's period or monthly revolution around Earth. → first quarter; → last quarter.

from O.Fr. quartier, from L. quartarius "fourth part," from quartus "fourth," related to quattuor "four," cognate with Pers. câr, cahâr, as below.

Cârak "quarter," literally "fourth, a fourth part of one," from câr, contraction of cahâr, → four, + -ak, contraction of yak, yek "one." Yek "one, alone," from Mid.Pers. êwak (Proto-Iranian *aiua-ka-); O.Pers. aiva- "one, alone;" Av. aēuua- "one, alone;" cf. Skt. éka- "one, alone, single;" Gk. oios "alone, lonely;" L. unus "one;" E. one.

quarter-wave plate
  تیغه‌ی ِ چارک-موج   
tiqe-ye cârak-mowj

Fr.: lame quart d'onde   

A plate of doubly refracting material cut parallel to the optic axis of the crystal and of such a thickness that a phase difference of 90° is introduced between the ordinary and extraordinary rays for light of a particular wavelength. → half-wave plate.

quarter; → wave; → plate.

quartic equation
  هموگش ِ چارُمیک   
hamugeš-e câromik

Fr.: équation quartique   

An equation containing unknowns of the fourth power; the general form: ax4 + bx3 + cx2 + dx + e = 0.

From L. quart(us) "fourth" (→ quarter) + → -ic; → equation.

hamugeš, → equation; câromân, from cârom "fourth," from câr, cahâr "four" + -om "-th" + -ik, → -ic.

quartile
  چارکوار   
cârakvâr

Fr.: quartile   

In statistics, any of the four groups of a frequency distribution each containing 25% of the total number of individual observations.

From M.L. quartilis, from quart(us) "fouth" + -ilis "-ile" a suffix of adjectives expressing capability, susceptibility, liability, aptitude.

Cârakvâr, from cârak, → quarter, + -vâr suffix of similarity, size, aptitude.

quartz
  کو‌آرتز   
kuârtz (#)

Fr.: quartz   

One of the most abundant → minerals in the Earth's → crust. Quartz is made up of silicon dioxide (SiO2), or → silica. It has marked → piezoelectric properties and → dielectric strength.

From Ger. Quarz "rock crystal," from M.H.G. twarc.

radio counterpart
  همتای ِ رادیویی   
hamtâ-ye râdio-yi

Fr.: contrepartie radio   

The representation in → radio wavelengths of an astronomical object that has emission in other parts of the → electromagnetic spectrum.

radio; → counterpart.

rare earth element
  بن‌پار ِ خاکی ِ کمیاب، خاک ِ کمیاب   
bonpâr-e xâki-ye kamyâb, xâk-e kamyâb

Fr.: terre rare   

Any of the group of metallic → chemical elements with → atomic numbers between 57 and 71 inclusive. The name is an inappropriate terminology, since they are neither rare nor earth; preferred name → lanthanide.

rare; → earth; → element.

relativistic particle
  ذرّه‌ی ِ بازانیگی‌مند   
zarre-ye bâzânigimand

Fr.: particule relativiste   

A particle which has a speed comparable to the velocity of light.

relativistic; → particle.

resonance particle
  ذرّه‌ی ِ باز‌آوایی   
zarre-e bâzâvâyi

Fr.: particule de résonance   

A hadronic particle which exists for only a very brief time (10-23 seconds) before decaying into hadrons; also called resonance. The existence of a resonance cannot be observed directly; it can only be inferred from studying the longer-lived products of its decay.

resonance; → particle.

set partition
  پرکش ِ هنگرد   
parkeš-e hangard

Fr.: partition d'un ensemble   

A collection of → nonempty subsets of a set A such that every element of A is in exactly one of the subsets. In other words, A is the → disjoint  → union of these subsets.

partition; → set.

Shack-Hartmann wavefront sensor
  حسگر ِ پیشان ِ موج ِ شک-هارتمان   
hessgar-e pišân-e mowj-e Shack-Hartmann

Fr.: analyseur de front d'onde   

An optical device, a modern version of the → Hartmann test, used for analyzing the wavefront of light. Theses sensors can be used to characterize the performance of optical systems. Moreover, they are increasingly used in real-time applications, such as → adaptive optics to remove the wavefront distortion before creating an image. It consists of a microlens array placed in front of a CCD array. A planar wavefront that is transmitted through a microlens array and imaged on the CCD array will form a regular pattern of bright spots. If, however, the wavefront is distorted, the light imaged on the CCD will consist of some regularly spaced spots mixed with displaced spots and missing spots. This information is used to calculate the shape of the wavefront that was incident on the microlens array.

Named after the German astronomer Johannes Hartmann (1865-1936), who first developed the method, and R. V. Shack, who in the late 1960s replaced the screen by a microlens array; → wavefront; → sensor.

shocked quartz
  کو‌آرتز ِ تشیده، ~ شوکیده   
kuârtz-e tošidé, ~ šokidé

Fr.: quartz choqué   

A form of quartz that has a deformed microscopic structure caused by intense pressure which alters the crystalline structure of quartz along planes inside the crystal. It was first discovered after underground nuclear bomb testing. It is found worldwide at the boundary between Cretaceous and Tertiary rocks. This is further evidence (in addition to iridium enrichment) that the transition between the two geological eras was caused by a large meteorite impact.

shock; → impact.

sink particle
  ذره‌ی ِ چاهک   
zarre-ye câhak

Fr.: particule puits   

In hydrodynamics codes, a way of treating a collapsing or accreting region, such as a star, as a simple → point mass. Indeed, in many situations, the scale of interest is much larger than the scale of the → accreting object itself and it would be impossible to perform the calculation otherwise. → Sinks are generally modeled as → Lagrangian particles (see, e.g., Bates et al. 1995, MNRAS 277, 362; Krumholz et al. 2004, ApJ 611, 399; Federrath et al. 2010, ApJ 713, 269).

sink; → particle.

Smoothed Particle Hydrodynamics (SPH)
  هیدروتوانیک ِ ذره‌های ِ همواریده   
hidrotavânik-e zarrehâ-ye hamvâridé

Fr.: hydrodynamique des particules lissées   

A numerical method for modeling → compressible hydrodynamic flows, which uses particles to simulate a continuous fluid flow. Because the system of hydrodynamical basic equations can be analytically solved only for few exceptional cases, the SPH method provides a numerical algorithm to solve systems of coupled → partial differential equations for continuous field quantities. The main advantage of the method is that it does not require a computational grid to calculate spatial → derivatives and that it is a Lagrangian method, which automatically focuses attention on fluid elements. The equations of motion and continuity are expressed in terms of ordinary differential equations where the body forces become classical forces between particles. This method was first independently developed by Lucy (1977, AJ 82, 1013) and Gingold & Monaghan (1977, MNRAS 181, 375).

Smoothed Particle Hydrodynamics, first used by Gingold & Monaghan (1977); → smooth; → particle; → hydrodynamics.

snowball Earth
  زمین ِ برف-گوله   
Zamin-e barf-gule

Fr.: Terre boule de neige   

Any of several episodes in the history of the Earth where our planet was entirely covered by glacial ice from pole to pole. There are at least three such episodes. The first one, called the Huronian glaciation, extended from 2.4 billion years ago to 2.1 billion years (lasting about 300 million years). In the last billion years, the Earth has experienced two more global glaciations: the Sturtian glaciation, which began 720 million years ago and, following a brief interglacial episode, the Marinoan glaciation, which ended 635 million years ago. During such episodes the global mean temperature would be about -50°C because most of the Sun's radiation would be reflected back to space by the icy surface. The average equatorial temperature would be about -20°C, roughly similar to present Antarctica. Without the moderating effect of the oceans, temperature fluctuations associated with the day-night and seasonal cycles would be greatly enhanced. Because of its solid surface, the climate on a snowball earth would have much in common with present Mars (http://www.snowballearth.org).

The term snowball Earth was coined in 1989 by Joe Kirschvink, a biomagnetist and paleomagnetist at the Caifornia Institute of Technology in Pasadena, USA; → earth.

standard model of particle physics
  مدل ِ استانده‌ی ِ فیزیک ِ ذره‌ای   
model-e estânde-ye fizik-e zarre-yi

Fr.: modèle standard de la physique des particules   

The theory developed since the 1970s, which is based on the theories and discoveries since the 1930s, and aims at explaining the fundamental structure of matter. According to the standard model, everything in the universe is made from a few basic building blocks called fundamental particles, governed by four fundamental forces. The particles occur in two basic types, called quarks and leptons. Three of the four fundamental forces (except gravity) and their carrier particles are included in the Standard Model. The Standard Model has successfully explained almost all experimental results and precisely predicted a wide variety of phenomena. Over time and through many experiments, the Standard Model has become established as a well-tested physics theory.

standard; → model; → particle; → physics.

star chart
  نگاره‌ی ِ ستارگان   
negâre-ye setâregân

Fr.: carte du ciel   

A chart or map showing the relative apparent positions of the stars as viewed from the Earth.

star; chart, from M.Fr. charte "card, map," from L. charta "leaf of paper, tablet," from Gk. khartes "layer of papyrus."

Negâré, from negâr "picture, figure," from negâštanPictor; setâregân plural of setâréstar.

strange particle
  ذره‌ی ِ شگفت   
zarre-e šegeft

Fr.: particule étrange   

An elementary particle created in high-energy particle collisions having a short life and a strangeness quantum number of 1. For example, sigma and xi baryons are strange particles. A strange particle is produced when a strange quark is created in a high-energy collision. → strangeness.

strange; the concept of "strange" arose from the observation that these particles decay rapidly, in contrast to others that do not. → particle.

subatomic particle
  ذره‌ی ِ زیر-اتمی   
zarre-ye zir-atomi (#)

Fr.: particule subatomique   

Any particle that is small compared to the size of the atom, e.g. an electron, proton, neutron, neutrino, quark, meson, all of which are either bosons or fermions.

subatomic; → particle.

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