Fr.: courbe d'absorption
A graphic representation of the amount of radiant energy absorbed by a material as a function of the wavelength.
Fr.: courbe analytique
A curve whose parametric equations are real → analytic functions of a single real variable.
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.
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
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.
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.
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.
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.
Fr.: courbe de Hugoniot
A curve, on the pressure versus specific volume plane, representing the locus of all the possible states that can be reached by a substance immediately after the passage of a single → shock wave. For each initial condition there is a different curve. No combustion occurs in the process and, therefore, the chemical composition of the medium does not change. See also → Rayleigh line; → Crussard curve.
Named after the French physicist Pierre Henri Hugoniot (1851-1887), who worked on fluid mechanics, especially flow properties before and after shock waves; → curve.