An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < AB con for Ind num rel sys > >>

Number of Results: 129 Search : system
AB magnitude system
  راژمان ِ بُرز ِ BA   
râžmân-e borz-e AB

Fr.: système de magnitudes AB   

A → photometric system defined by reference to → monochromatic magnitudes in such a way that, when monochromatic → flux fν is measured in ergs sec-1 cm-2 Hz-1, the magnitude will be: AB = -2.5 logfν - 48.60. The constant is set so that AB is equal to the V magnitude for a source with a flat → spectral energy distribution. The → zero point is defined by the flux of the star → Vega at 5546 Å. In this system, an object with constant flux per unit frequency interval has zero color.

magnitude; → system.

accelerating system
  راژمان ِ شتابنده   
râžmân-e šetâbandé

Fr.: système en accélération   

A material system that is subject to a constant force in each and every one of its instantaneous points of trajectory.

accelerating; → system.

adaptive optics system
  راژمان ِ نوریک ِ نیاوشی   
râžmân-e nurik-e niyâveši

Fr.: système d'optique adaptative   

An → optical system that uses → adaptive optics.

adaptive; → optics; → system.

afocal system
  راژمان ِ اکانون   
râžmân-e akânun

Fr.: système afocal   

An optical system with object and image points at infinity.

afocal; → system.

Alpha Centauri system
  راژمان ِ آلفا-کنتا‌ؤرس   
râžmân-e Âlfâ-Kentâwros

Fr.: système Alpha du Centaure   

A system of three stars, the → close binary Alpha Centauri A (→ spectral type G2 V) and Alpha Centauri B (K1 V), and a small and faint → red dwarf, Alpha Centauri C (M6 Ve), better known as → Proxima Centauri. To the unaided eye, the two main components (AB) appear as a single object with an → apparent visual magnitude of -0.27, forming the brightest star in the southern constellation → Centaurus and the third brightest star in the night sky, after → Sirius and → Canopus. The individual visual magnitudes of the components A, B, and Proxima are +0.01, +1.33, and +11.05, respectively. The masses of A and B are 1.100 and 0.907 Msun, respectively. Their → effective temperatures are (A) 5,790 K and (B) 5,260 K; their luminosities (A) 1.519 Lsun and (B) 0.500 Lsun. The binary members are separated in average by only 23 → astronomical units. They revolve around a common center of mass with a period of about 80 years. Both have a distance of 4.37 → light-years. Proxima Centauri, lying about 15,000 AU apart from AB, is → gravitationally bound to them. It has a mass of 0.1 Msun, a radius of 0.1 Rsun, a luminosity of about 0.001 Lsun, and an → effective temperature of ~ 3,000 K.

alpha; → Centaurus; → system.

altazimuth coordinate system
  راژمان ِ هم‌آراهای ِ فرازا-سوگان   
râžmân-e hamârâhâ-ye farâzâ-sugân

Fr.: coordonnées azimutales   

The coordinate system in which the position of a body on the → celestial sphere is described with respect to an observer's → celestial horizon and → zenith. The coordinates of a point in this system are its → altitude on the → vertical circle, and its → azimuth westward (clockwise) along the celestial horizon from the observer's south. Same as → horizon coordinate system.

altazimuth; → coordinate; → system.

anamorphic system
  راژمان ِ آناریخت، ~ آناریخت‌مند   
râžmân-e ânârixt, ~ ânârixtmand

Fr.: système anamorphique   

An optical system whose optical power, and imaging scale, differs in the two principal directions. See also → anamorphosis.

anamorphic; → system.

aplanatic system
  راژمان ِ نابیراه   
râžmân-e nâbirah

Fr.: système aplanétique   

An → optical system that is able to produce an image essentially free from → spherical aberration and → coma. See also the → Abbe sine condition.

aplanatism; → system.

apochromatic system
  راژمان ِ اپافام   
râžmân-e apâfâm

Fr.: système apochromatique   

An optical system that is → apochromatic.

apochromatic; → system.

axiomatic system
  راژمان ِ بنداشتی   
râžmân-e bondâšti

Fr.: système axiomatique   

Any system of → logic which explicitly states → axioms from which → theorems can be → deduced.

axiomatic; → system.

binary number system
  راژمان ِ عددهای ِ درینی   
râžmân-e adadhâ-ye dirini

Fr.: système des nombres binaires   

A → numeral system that has 2 as its base and uses only two digits, 0 and 1. The positional value of each digit in a binary number is twice the place value of the digit of its right side. Each binary digit is known as a bit. The decimal numbers from 0 to 10 are thus in binary 0, 1, 10, 11, 100, 101, 110, 111, 1000, 1001, and 1010. And, for example, the binary number 111012 represents the decimal number (1 × 24) + (1 × 23) + (1 × 22) + (0 × 21) + (1 × 20), or 29. In electronics, binary numbers are the flow of information in the form of zeros and ones used by computers. Computers use it to manipulate and store all of their data including numbers, words, videos, graphics, and music.

binary; → number; → system.

binary system
  راژمان ِ درین   
râžmân-e dorin

Fr.: système binaire   

Two astronomical objects revolving around their common center of mass.

binary; → system.

Râžmân, → system; dorinbinary.

bound system
  راژمان ِ بندیده   
râžmân-e bandidé

Fr.: système lié   

A system composed of several material bodies the total energy of which (the sum of kinetic and potential energies) is negative, e.g. a → bound cluster.

Bound, p.p. of → bind; → system.

Aâžmân, → system; bandidé p.p. of bandidan, → bind.

catoptric system
  راژمان ِ بازتابیک   
râžmân-e bâztâbik

Fr.: système catoprtique   

An optical system in which the light is reflected only.

catoprtics; → system.

CGS system
  راژمان ِ CGS   
râžmân-e CGS

Fr.: système CGS   

The system of → CGS units.

CGS unit; → system.

chaotic system
  راژمانِ ورشونگین   
râžmân-e varšungin

Fr.: système chaotique   

A system that is → deterministic through → description by mathematical rules but can evolve highly → nonlinearly depending on → initial conditions. See also → chaos.

chaotic; → system.

close binary system
  راژمان ِ دورین ِ کیپ   
râžmân-e dorin-e kip

Fr.: système binaire serré   

A → binary system in which the distance separating the stars is comparable to their size. Most close binaries are spectroscopic binaries (→ spectroscopic binary) and/or eclipsing binaries (→ eclipsing binary). In most of them → mass transfer occurs at some stage, an event which profoundly affects the → stellar evolution of the components. The evolution of close binaries depends on the → initial masses of the two stars and their → separation. When the more massive star evolves into a → red giant first, material will spill through the inner point onto its companion, thereby affecting its companion's evolution. Mass transfer can also alter the separation and → orbital period of the binary star.

close; → binary; → system.

closed system
  راژمان ِ بسته   
râžmân-e basté

Fr.: système fermé   

Thermodynamics: A system which can exchange energy with the surroundings but not matter. → open system; → isolated system.

closed; → system.

compact binary star system
  راژمان ِ درین ِ همپک   
râžmân-e dorin-e hampak

Fr.: système binaire compact   

A binary star system which is composed of a collapsed object (→ degenerate dwarf, → neutron star, or → black hole) in orbit with a low-mass (≤ 0.5 Msol) secondary star, wherein the collapsed star → accretes matter from its → companion. These two objects form a binary system of overall dimensions 106 km with an orbital period of only hours or less. See also: → X-ray binary.

compact; → binary; → star; → system.

conservative system
  راژمان ِ پایش‌مند   
râžmân-e pâyešmand

Fr.: système conservatif   

A system in which there is no dissipation of energy so that the total energy remains unchanged with time.


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