# An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 5 Search : multiplier
 force multiplier parameter   پارامون ِ بستاگر ِ نیرو   pârâmun-e bastâgar-e niruFr.: paramètre de multiplicateur de force   One of the three quantities (k, α, and δ) which are used in the → radiation-driven wind theory to express the radiation pressure due to spectral lines. These coefficients parametrize the radiation acceleration as: grad≅ k(dv/dr)αge, where ge = σeL/4πcR*2 is the radiative acceleration by electron scattering. The parameter k is dependent on the number of lines that produce the radiation pressure. The parameter α depends on the optical depth of the driving lines and varies between 0 (optically thin) and 1 (optically thick). The parameter δ describes the dependence of k on the density with k ≅ ρδ. The velocity law of radiation-driven winds depends on α and δ, but not on k. The → mass loss rate depends on k, α, and δ (Castor et al. 1975, ApJ 195, 157; Lamers et al., 1995, ApJ 455, 269 and references therein).→ force; → multiplier; → parameter. Lagrangian multiplier   بستاگر ِ لاگرانژ   bastâgar-e LagrangeFr.: multiplicateur de Lagrange   Math.: A constant that appears in the process for obtaining extrema of functions of several variables. Suppose that the function f(x,y) has to be maximized by choice of x and y subject to the constraint that g(x,y)≤ k. The solution can be found by constructing the → Lagrangian function  L(x,y,λ) = f(x,y) + λ[k - g(x,y)], where λ is the Lagrangian multiplier. least common multiplier (LCM)   کوچکترین بستاگر ِ همدار   kucektarin bastâgar-e hamdârFr.: plus petit commun multiple   Of two or more → integers, the smallest positive number that is divisible by those integers without a remainder.→ least; → common; → multiplier. multiplier   بستاگر   bastâgarFr.: multiplicateur   Arithmetic: A number by which another is multiplied. Physics: A device for intensifying some effect.Agent noun of → multiply. photomultiplier   شید-بستاگر، نور-بستاگر   šid-bastâgar, nur-bastâgarFr.: photomultiplicateur   Electronic tube which converts photons into electrons, multiplies the electrons via a series of electrodes, and produces a measurable current from a very small input signal.→ photo- + → multiplier.