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: 24 Search : structure
bottom-up structure formation
  دیسش ِ ساختار از پایین به بالا   
diseš-e sâxtâr az pâyin bé bâlâ

Fr.: formation des structures du bas vers le haut   

A → structure formation scenario in which small galaxies form first, and larger structures are then formed in due course. Contrary to → top-down structure formation.

bottom; → up; → structure; → formation; → galaxy.

causal structure
  ساختار ِ بنارمند   
sâxtâr-e bonârmand

Fr.: structure causale   

In → special relativity, the causal relationship between → events involving a → light cone.

causal; → structure.

crystal structure
  ساختار ِ بلور   
sâxtâr-e bolur

Fr.: structure de cristal   

The geometric framework to which a crystal may be referred and the arrangement of atoms or electron density distribution relative to that framework, usually determined by X-ray diffraction measurements.

crystal; → structure.

crystalline structure
  ساختار ِ بلورین   
sâxtâr-e bolurin

Fr.: structure cristalline   

An arrangement and interrelationship of parts that is of → crystalline nature.

crystalline; → structure.

data structure
  ساختار ِ داده‌ها   
sâxtâr-e dâdehâ

Fr.: structure de données   

A → method or → format for organizing and storing data. Any data structure is designed to organize data to suit a specific purpose so that it can be accessed and worked with in appropriate ways. In computer programming, a data structure may be selected or designed to store data for the purpose of working on it with various algorithms.

data; → structure.

fine structure
  ساختار ِ نازک   
sâxtâr-e nâzok

Fr.: structure fine   

Closely spaced components seen at high resolution in a → spectral line. The phenomenon is explained by the fact that instead of a single → energy level corresponding to a given value of the → quantum number  n, there are actually a number of energy levels lying close to one another. → fine-structure constant, → fine-structure line.

fine; → structure.

fine-structure constant
  پایای ِ ساختار ِ نازک   
pâyâ-ye sâxtâr-e nâzok

Fr.: constante de la structure fine   

A measure of the strength of → interaction between a → charged particle and the → electromagnetic field. It is a → dimensionless number expressed (in → cgs units) by α = e2c, where e is the → electron charge, ħ is the → reduced Planck's constant, and c is the → speed of light. It is approximately equal to 1/137 or 7.3 x 10-3. The smallness of this number is of great importance since it determines the size of → atoms and the → stability of → matter.

fine structure; → constant.

fine-structure line
  خط با ساختار ِ نازک   
xatt bâ sâxtâr-e nâzok

Fr.: raie de structure fine   

A → spectral line whose → energy levels have a → fine structure. Examples are [C II] 157.7 μm (→ singly ionized carbon), [O III] 88 μm, and [Ne II] 12.8 μm.

fine; → structure; → line.

fractal structure
  ساختار ِ برخالی   
sâxtâr-e barxâli

Fr.: structure fractale   

A → hierarchial structure that can be likened to fractals.

fractal; → structure

galactic structure
  ساختار ِ کهکشان   
sâxtâr-e kahkešân

Fr.: structure galactique   

The global shape and the arrangement of the various parts or constituents of a galaxy.

galactic; → structure.

hierarchical structure formation
  دیسش ِ ساختار ِ پایگانی   
diseš-e sâxtâr-e pâygâni

Fr.: formation de structures hiérarchiques   

A cosmological → structure formation model in which the smallest gravitationally bound structures (→ quasars and galaxies) form first, followed by → groups, → galaxy clusters, and → superclusters of galaxies.

hierarchical; → structure; → formation.

hyperfine structure
  ساختار ِ اَبَرنازک   
sâxtâr-e abar-nâzok (#)

Fr.: structure hyperfine   

In spectroscopy, the → splitting of a spectral line into a number of very thin components. It results from a small perturbation in the energy levels of atoms or molecules due to the magnetic dipole-dipole interaction arising from the interaction of the nuclear → magnetic moment with the → spin of the electron. It can be observed only at high spectral dispersion. → fine structure.

hyperfine; → structure.

internal structure of stars
  ساختار ِ درونی ِ ستارگان   
sâxtâr-e daruni-ye setâregân (#)

Fr.: structure interne des étoiles   

The physical characteristics of that part of a star lying below the → photosphere. More specifically, the study of its various zones (→ core, → convective zone, → radiative zone) and the transfer of energy through them.

internal; → structure; → star.

large-scale structure
  ساختار ِ بزرگ-مرپل   
sâxtâr-e bozorg-marpel

Fr.: structure à grandes échelles   

The distribution of galaxies and other forms of mass on large distance scales, covering hundreds of millions of → light-years.

large; → scale; → structure.

megastructure
  مگاساختار   
megâsâxtâr

Fr.: mégastructure   

Same as → Dyson sphere.

mega-; → structure.

random structure
  ساختار ِ کاتوره   
sâxtâr-e kâturé

Fr.: structure aléatoire   

Crystalline arrangement in which equivalent positions are not necessarily occupied by atoms of a single kind.

random; → structure.

relational data structure
  ساختار ِ داده‌های ِ بازانشی   
sâxtâr-e dâdehâ-ye bâzâneši

Fr.: structure de données relationnelle   

A type of data structure in which data are represented as tables in which no entry contains more than one value.

relational; → data; → structure.

spiral structure
  ساختار ِ مارپیچ   
sâxtâr-e mârpic

Fr.: structure spirale   

The morphology of a galaxy which displays → spiral arms.

spiral; → structure.

stellar structure
  ساختار ِ ستاره، ~ ستاره‌ای   
sâxtâr-e setâré, ~ setêre-yi

Fr.: structure stellaire   

A physical model that describes the internal arrangement of a star in detail and makes detailed predictions about the luminosity, the color, and the future evolution of the star.

stellar; → structure.

stellar structure equation
  هموگش ِ ساختار ِ ستاره   
hamugeš-e sâxtâr-e setâré

Fr.: équation de structure stellaire   

A set of → differential equations describing the physical properties of stars based on two main assumptions: a star is a perfect sphere and the net force on a macroscopic mass element is zero. If the effects of rotation and magnetism are ignored, these assumptions lead to a set of five differential equations.

stellar; → structure; → equation.

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