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.
Fr.: courbe analytique
A curve whose parametric equations are real → analytic functions of a single real variable.
atomic volume curve
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.
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).
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.
Fr.: courbe caustique
The intersection of a → caustic surface with a plane passing through the beam of rays.
Fr.: courbe caractéristique
Graph representing an optical film's response to the amount of light falling on it.
→ characteristic; → curve.
xam-e basté (#)
Fr.: courbe fermée
A curve whose ends are joined.
Fr.: courbe composée
A curve that is made up of a series of successive tangent circular arcs.
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.
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."
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 of growth
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.
Adj. from → curve.
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.
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.
xam-e nemâyi (#)
Fr.: courbe exponentielle
A curve that represents an → exponential function.
→ exponential; → curve.
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
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.
flat rotation curve
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.