An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 1358
chemical enrichment
  پرداری ِ شیمیایی   
pordâri-ye šimiyâyi

Fr.: enrichissement chimique   

The → process by which the relative → abundance of a given → chemical element or → species in an → astrophysical object is increased. For example the the → increase of the → heavy element content of the → interstellar medium due to → stellar evolution.

chemical; → enrichment.

chemical equation
  هموگش ِ شیمیایی   
hamugeš-e šimiyâyi

Fr.: équation chimique   

The symbolic representation of a chemical reaction where the formulae of the → reactants are placed on the left and the formulae of → products on the right of an arrow.

chemical; → equation.

chemical evolution
  فرگشت ِ شیمیایی   
fargašt-e šimiyâyi (#)

Fr.: évolution chimique   

A cumulative change in the chemical properties, or more specifically, the relative abundances of chemical elements in an astrophysical system.

chemical; → evolution.

chemical mixing
  آمیزش ِ شیمیایی، ~ شیمیک   
âmizeš-e šimiyâyi, ~ šimik

Fr.: mélange chimique   

mixing process.

chemical; → mixing.

chemical potential
  توند ِ شیمیک   
tavand-e šimik

Fr.: potentiel chimique   

For a given component in a → gas mixture, the change in → Gibbs free energy (G) with respect to change in amount of the component (n), when pressure, temperature, and amounts of other components remain constant: ∂G/∂n. Components are in equilibrium if their chemical potentials are equal.

chemical; → potential.

chemical reaction
  واژیرش ِ شیمیایی، واکنش ِ ~   
vâžireš-e šimiyâyi, vâkoneš-e ~

Fr.: réaction chimique   

A → change or → transformation in which a → substance → decomposes, → combines with other → substances, or interchanges constituents with other substances.

chemical; → reaction.

chemical separation
  جدایی ِ شیمیایی   
jodâyi-ye šimiyâyi

Fr.: séparation chimique   

The physical processes that can cause certain elements to migrate in a → stellar atmosphere. These processes are thought to be important in creating the chemical peculiarities seen in → Am stars and → Ap stars.

chemical; → separation.

chemical species
  آرز ِ شیمییایی   
âraz-e šimiyâyi

Fr.: espèce chimiique   

A set of chemically → identical  → atomic or → molecular entities.

chemical; → species.

chemically peculiar star
  ستاره‌ی ِ شیمیکانه افد   
setâre-ye šimikâné afd

Fr.: étoile chimiquement particulière   

A → main sequence star of → spectral type A or B (→ A-type star, → B-type star) identified by the presence of anomalously strong or weak → absorption lines of certain elements in their spectra. CP stars have been divided into four main classes on the basis of their spectra: 1) non-magnetic metallic-lined (CP1, → Am star), magnetic (CP2, → Ap star), non-magnetic mercury-manganese (CP3, → HgMn star), and helium-weak (CP4, → He-weak star).
See also → Ap/Bp stars.

chemical; → -ly; → peculiar; → star.


Fr.: chimiluminescence   

The production and emission of light via a → chemical reaction.

Chemi-, → chemo-; → luminescence.


Fr.: chimisorption   

A kind of → adsorption in which the forces involved are → valence forces of the same kind as those operating in the formation of → chemical compounds. Same as → chemical adsorption. See also → physisorption.

Chemi-, from → chemical; → sorption.

šimi (#)

Fr.: chimie   

The science of the composition, structure, properties, and reactions of chemical elements and compounds and their interactions with matter and energy.

Chemistry, from chemist, from Gk. chemia "alchemy" + -ry, from M.E. -rie, from O.Fr.

Šimi, from Fr. as above.

šimi- (#)

Fr.: chimio-   

A combining form meaning "chemical, chemically induced, chemistry," used in the formation of compound terms like → chemosynthesis. Also chem- (before a vowel) and chemi- (before elements of L. origin).

Chemo- extracted from → chemical or → chemistry.


Fr.: chimiosynthèse   

In biochemistry, the ability to produce organic compounds using energy contained in inorganic molecules. Chemosynthesis is similar to → photosynthesis. Instead of using light as an energy source to make food, energy or compounds from chemical reactions is used. Most chemosynthetic organisms are bacteria.

chemo-; → synthesis.


Fr.: Cheops   

The first mission, conducted by the → European Space Agency, dedicated to searching for → exoplanetary transits by performing ultra-high precision → photometry on bright stars already known to host planets. Launched on 18 December 2019, Cheops is a small spacecraft with a launch mass (including propellant) of approximately 280 kg. It has a single instrument: a high precision → photometer with a 300 mm effective aperture telescope and a single → charge-coupled device (CCD) → detector covering → visible to → near-infrared wavelengths. The mission's main science goals are to measure the bulk density of → super-Earths and Neptunes orbiting bright stars and provide suitable targets for future in-depth characterization studies of → exoplanets in these mass and size ranges.

CHEOPS, short for CHaracterising ExOPlanet Satellite.

Cherenkov radiation
  تابش ِ چرنکوف   
tâbeš-e Čerenkov (#)

rayonnement de Čerenkov   

Visible radiation emitted when → charged particles pass through a transparent medium faster than the speed of light in that medium.

Named after Pavel A. Čerenkov (1904-1990), Russian physicist, who discovered the phenomenon. He shared the Nobel prize 1958 in physics with Ilya Frank and Igor Tamm, who in 1937 gave the theoretical explanation for this radiation.

chi-square distribution
  واباژش ِ خی-دو   
vâbâžeš-e Xi-do

Fr.: loi du chi-deux   

A probability density function, denoted χ2, that gives the distribution of the sum of squares of k independent random variables, each being drawn from the normal distribution with zero mean and unit variance. The integer k is the number of degrees of freedom. The distribution has a positive skew; the skew is less with more degrees of freedom. As degrees of freedom increase, the chi-square distribution approaches a normal distribution. The most common application is chi-square tests for goodness of fit of an observed distribution to a theoretical one. If χ2 = 0 the agreement is perfect.

Chi Gk. letter of alphabet; → square; → distribution.

Vâbâžeš, → distribution; do, → two.

Chicxulub crater
  لاوک ِ چیکخولوب   
lâvak-e Cikxulub

Fr.: Cratère de Chicxulub   

A crater about 200 km in diameter on the northern coast of the Yucatan Peninsula, near the town of Chicxulub, Mexico. It is attributed to a 10 km wide → asteroid that hit the Earth about 65 million years ago (→ Chicxulub impactor). Ten years before the 1990 discovery of the Chicxulub crater, physicist Luis Alvarez and geologist Walter Alvarez proposed a theory to explain the formation of the crater. They noted increased concentrations of the element → iridium in 65-million-year-old clay. Iridium is rare on Earth, but it's more common in some objects from space, like → meteors and asteroids. According to the Alvarez theory, a massive asteroid had hit the Earth, blanketing the world in iridium. The collision caused fires, climate change and widespread extinctions, among which that of dinosaurs, who had lived for 180 million years.

Named after a twon in the Mexican state of Yucatan, which lies near the geographic center of the → crater.

Chicxulub impactor
  برخوردگر ِ چیکخولوب   
barxordgar-e Cikxulub

Fr.: impacteur de Chicxulub   

An object having an estimated mass between 1.0 × 1015 and 4.6 × 1017 kg, which struck the Earth at the → Cretaceous-Tertiary event about 65 million years ago. It was probably an → asteroid 10 km in diameter with a velocity of roughly 20 km per sec at an angle of just under 60°. The collision created the → Chicxulub crater. The event was responsible for eliminating approximately 70 percent of all species of animals at or very close to the boundary between the Cretaceous and Paleogene periods.

Chicxulub crater; → impactor.

farzand (#)

Fr.: enfant   

1) A person between birth and puberty; a son or daughter; an offspring.
2) In → graph theory, the → vertex (node) below a given vertex connected by its → edge downward. In other words, in a rooted tree, a vertex v is a child of vertex w if v immediately succeeds w on the path from the root to v. Vertex v is a child of w if and only if w is the parent of v.

M.E.; O.E. cild "fetus, infant;" akin to Goth. kilthai "womb."

Farzand, from Mid.Pers. frazand "child;" Av. frazanti- "progeny, offspring," from fra- "forward, along," → pro-, + zan "to give birth;" → birth.

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