ON THE STARK BROADENING OF Si III SPECTRAL LINES IN STELLAR PLASMA MILAN S. DIMITRIJEVIĆ1, ZORAN SIMIĆ1, SYLVIE SAHAL-BRÉCHOT2 1Astronomical Observatory, Volgina 7, 11060 Belgrade, Serbia 2LERMA, Observatoire de Paris, Meudon, France E-mail: mdimitrijevic@aob.rs, zsimic@aob.rs, sylvie.sahal-brechot@obspm.fr

Silicon atoms and ions in various ionisation stages are present in cosmic plasma and the Stark broadening of the their spectral lines is important for analysis, investigation and modelling of stellar plasma, especially for white dwarfs and hot stars of A and late B spectral type. They are also of interest for example for research and synthesis of stellar spectra, abundance determinations and radiative transfer calculations. In order to provide the needed Stark broadening parameters, calculations have been performed for a number of Si III spectral lines broadened by electron-, proton-, and helium ion-impacts, by using the semiclassical perturbation theory.

Example: PERTURBER DENSITY = 1.E+17cm-3 ELECTRONS PROTONS He III TRANSITION T(K) WIDTH(A) SHIFT(A) WIDTH(A) SHIFT(A) WIDTH(A) SHIFT(A) SiIII 4D 5F 10000. 2.54 -0.740E-01 0.141 -0.961E-01 4718.0 A 20000. 2.11 -0.453E-01 0.200 -0.141 C= 0.11E+20 50000. 1.70 -0.285E-01 0.272 -0.196 *0.523 -0.380 100000. 1.45 -0.206E-01 0.340 -0.231 *0.612 -0.467 150000. 1.32 -0.144E-01 0.388 -0.253 *0.662 -0.506 300000. 1.13 -0.157E-01 0.481 -0.283 *0.754 -0.568

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