independent random variables
vatandehâ-ye kâture-ye nâvâbasté
Fr.: variables aléatoires indépendantes
Statistics: Two random variables X and Y if and only if the value of X has no influence on the value of Y and vice versa.
Fr.: variable indépendante
Math.: A variable whose value determines the value of other variables. For example, x, in the expression y = f(x), is the independent variable. See also → dependent variable.
Fr.: variable individuel
In → predicate logic, a variable which represents an unspecified → subject. Individual variables work just as do variables in algebra, they stand in for a value, but have no fixed value of their own. They are represented by lower case letters taken from the end of the alphabet x, y, z; and if additional variables are needed by u, v, w, as well.
Fr.: variable intrinsèque
A variable star whose fluctuations in brightness are due to natural changes in the luminosity of the star itself, not by external causes, such as in → extrinsic variable stars.
Fr.: plan invariable
Mechanics: For a rotating rigid body not subject to external torque, a plane which is perpendicular to the angular momentum vector of the body, and which is always tangent to its → inertia ellipsoid.
Fr.: variable irrégulière
A type of variable star in which variations in brightness show no regular periodicity. There are two main types, irregular eruptive variables and irregular pulsating variables.
Fr.: variable linguistique
vartande-ye derâz dowré
Fr.: variable à longue période
Luminous Blue Variable (LBV)
vartande-ye âbi-ye tâbân
Fr.: variable bleue lumineuse
A high-luminosity variable star, which represents a transition phase in the life of a massive star when it evolves off the main sequence to become a supernova. Only about a dozen confirmed LBVs are presently known in our Galaxy. → Hubble-Sandage variable.
Fr.: variables de type Mira
Fr.: variable nébulaire
A type of eruptive variable star, mainly young FU Orionis and T Tauri types, associated with nebulosity.
optically violent variable (OVV) quasar
kuâsâr-e vartande-ye nurâné surâ
Fr.: quasar variable optiquement violent
A member of a small subset of quasars consisting of bright radio galaxies whose flux of visible light output can vary by as much as 50% in a single day.
periodically variable supergiant (PVSG)
abarqul-e vartande-ye dowreyi
Fr.: supergéante variable périodiquement
A variable → supergiant star with typical periods of the order of 10 to 100 days and amplitudes less than a few tenths of a magnitude. PVSGs are thought to be pulsating → g modes, caused by a density inversion, arising from an → opacity bump, most likely from Fe, H, and/or He.
Fr.: variable propositionnel
Fr.: variable aléatoire
real dynamical variable
vartande-ye tavânik-e hasyâ
Fr.: variable dynamique réel
Fr.: variable semirégulière
A type of giant or supergiant pulsating variable star, with intermediate or late spectra, showing noticeable periodicity in its light changes, accompanied or sometimes interrupted by various irregularities. Periods lie in the range from 20 to more than 2000 days, while the shapes of the light curve may be rather different and variable with each cycle. The amplitudes may be from several hundredths to several magnitudes (usually 1-2 magnitudes in the V filter). Examples are Betelgeuse, Antares, and Rasalgethi. Semiregular variables are classified in several subtypes: SRA, SRB, SRC, and SRD.
Fr.: variable à courte période
A variable star that has a relatively short period with respect to stars of similar types.
Fr.: variable spectroscopique
Something that may or does vary. → variable star.
M.E., from O.Fr. variable, from L. variabilis "changeable," from variare "to change," → vary.
Vartandé agent noun from vartidan "to change," → vary.