An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < abs Hug > >>

Number of Results: 36 Search : curve
absorption curve
  خم ِ درشم   
xam-e daršam

Fr.: courbe d'absorption   

A graphic representation of the amount of radiant energy absorbed by a material as a function of the wavelength.

absorption; → curve.

analytic curve
  خم ِ آنالسی   
xam-e ânâlasi

Fr.: courbe analytique   

A curve whose parametric equations are real → analytic functions of a single real variable.

analytic; → curve.

atomic volume curve
  خم ِ گنج ِ اتمی   
xam-e gonj-e atomi

Fr.: courbe du volume atomique   

A graph displaying → atomic volumes of → chemical elements against their → atomic masses, first plotted by Lother Meyer (1830-1895). The elements with similar properties occupy the same positions on the graph. In the original curve, Lothar Meyer plotted atomic volumes against → atomic weights. → Alkali metals such as Na, K, Rb, and Cs occupy the top position on the graph. Elements like Be, Mg, Ca, Sr, and Ba occupy the positions on the ascending part of the graph. → Inert gases, except He, occupy the positions on the descending part of the graph. → Halogen elements like F, Cl, and Br also occupy the descending part of the graph.

atomic; → volume; → curve.

blackbody curve
  خم ِ سیه‌جسم   
xam-e siyah-jesm

Fr.: courbe de corps noir   

The characteristic way in which the → intensity of → radiation emitted by a → blackbody varies with its → frequency (or → wavelength), as described by → Planck's radiation law. Also referred to as the → Planck curve. The exact form of the curve depends only on the object's → temperature. The wavelength at which the emitted intensity is highest is an indication of the temperature of the radiating object. As the temperature of the blackbody increases, the peak wavelength decreases (→ Wien's displacement law) and the total energy being radiated (the area under the curve) increases rapidly (→ Stefan-Boltzmann law).

blackbody; → curve.

calibration curve
  خمِ کبیزش   
xam-e kabizeš

Fr.: courbe d'étalonnage   

An empirical curve obtained through appropriate exposures in order to determine the instrument's response. For example, a curve allowing the conversion of relative intensities of an observed object into absolute fluxes, or a curve relating the detector's pixel positions to wavelengths.

calibration; → curve.

caustic curve
  خم ِ سوچان   
xam-e sucân

Fr.: courbe caustique   

The intersection of a → caustic surface with a plane passing through the beam of rays.

caustic; → curve.

characteristic curve
  خم ِ سرشتاری   
xam-e sereštâri

Fr.: courbe caractéristique   

Graph representing an optical film's response to the amount of light falling on it.

characteristic; → curve.

closed curve
  خم ِ بسته   
xam-e basté (#)

Fr.: courbe fermée   

A curve whose ends are joined.

closed; → curve.

compound curve
  خم ِ همنات   
xam-e hamnât

Fr.: courbe composée   

A curve that is made up of a series of successive tangent circular arcs.

compound; → curve.

Crussard curve
  خم ِ کروسار   
xam-e Crussard

Fr.: courbe de Crussard   

A curve, on the pressure versus specific volume plane, representing the locus of all the theoretically possible states that can be attained by the → detonation products of an → explosive. The Crussard curve relates to the → Hugoniot curve through a translation caused by the chemical energy liberated during the detonation. The Crussard curve consists of several portions characterizing various burning regimes: detonations (strong and weak), a forbidden region, and → deflagrations (weak and strong).

Named after the French engineer Jules Louis Crussard (1876-1959), who conducted several pioneering studies in mining techniques, in particular on shock waves (Ondes de choc et onde explosive, Bulletin de la Société de l'industrie minérale de Saint-Etienne, 4e série, tome VI, 1907); → curve.

xam (#)

Fr.: courbe   

A line that deviates from straightness in a smooth, continuous fashion. A line representing a variable on a graph.

From L. curvus "crooked, curved, bent;" cf. Av. skarəna- "round," Gk. kirkos, krikos "a ring;" PIE base *sker- "to turn, bend."

Xam, variant kamân "arc," Mid.Pers. kamân, probably from PIE *kamb- "to bend, crook," cf. Breton kamm "curved, bent."

curve fitting
  سز ِ خم، سزکرد ِ ~   
saz-e xam, sazkard-e ~

Fr.: ajustement de courbe   

Construction of mathematical functions whose graphs are curves that "best" approximate a given collection of data points.

curve; → fitting.

curve of growth
  خم ِ رویش   
xam-e ruyeš

Fr.: courbe de croissance   

A plot showing how the → equivalent width of an → absorption line, or the radiance of an → emission line, increases as a → function of the → number of → atoms that produce the line.

curve; → growth.

xamidé (#)

Fr.: courbé   

Not straight.

Adj. from → curve.

dispersion curve
  خم ِ پاشش   
xam-e pâšeš

Fr.: courbe de dispersion   

A graph displaying the variation of the → refractive index of a substance against the wavelength of the electromagnetic wave passing through the substance.

dispersion; → curve.

drift curve
  خم ِ دلک   
xam-e delek

Fr.: courbe de passage   

In radio astronomy, the output response as a function of position for a given filter as the source passes through the beam.

drift; → curve.

exponential curve
  خم ِ نمایی   
xam-e nemâyi (#)

Fr.: courbe exponentielle   

A curve that represents an → exponential function.

exponential; → curve.

extinction curve
  خم ِ خاموشی   
xam-e xâmuši

Fr.: courbe de l'extinction interstellaire   

A graph representing the variation of the → interstellar extinction against → wavelength. Usually it displays the → normalized values of extinction as a function of (the → inverse) of the wavelength (in → microns). See, e.g., Sandage & Mathis, 1979, Ann. Rev. Astron. Astrophys. 17, 73.

extinction; → curve.

family of curves
  خانواده‌ی ِ خمها   
xânevâde-ye xamhâ

Fr.: famille de courbes   

A set of similar curves which are distinguished by the values taken by one or more parameters in their general equation. For example, the general solution of a differential equation is represented by a family of curves.

family; → curve.

flat rotation curve
  خم ِ چرخش ِ تخت   
xam-e carxeš-e taxt

Fr.: courbe de rotation plate   

A galactic → rotation curve in which the → rotation velocity is constant in the outer parts. The flat component is preceded by a rising curve that shows solid body rotation in the very center of the → galaxy. A flat rotation curve implies that the mass is still increasing linearly with radius. See also → dark matter.

flat; → rotation; → curve.

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