Stark widths of Ar III spectral lines in the atmospheres of subdwarf B stars

Abstract

Using semiclassical perturbation approach in impact approximation, we have calculated Stark widths for 32 spectral lines of doubly charged argon (Ar III). Oscillator strengths are calculated using Hartree-Fock method with relativistic correction (HFR) and an atomic model including 17 configurations. Energy levels are taken from NIST database. For perturbing levels for which the corresponding energy does not exist in NIST database, the calculated energies are used. Our widths are compared with the experimental results. The results presented here are of interest for modelling and investigation of stellar atmospheres since argon in different ionization stages is observed in many astrophysical objects. Finally, the importance of Stark broadening mechanism is studied in the atmospheric conditions of sdB stars. Electron impact Stark widths are compared to thermal Doppler widths as a function of temperature and optical depth of atmospheric layers.

Stark Widths of Ar II Spectral Lines in the Atmospheres of Subdwarf B Stars

“…The influence of Stark broadening in DO white dwarf atmospheres was also studied by Dimitrijević et al [12] using Xe VIII spectral lines and similar conclusions were found. Hamdi et al [13] studied the importance of Stark broadening in the atmospheres of subdwarf B stars using Ar III spectral lines. It was demonstrated that this mechanism is important, especially for atmospheres with high values of log g.…”

On the Stark broadening of some Cr II spectral lines in plasma

“…Chromium in various ionization stages has been observed in the spectra of white dwarf atmospheres, where the Stark broadening is usually dominant broadening mechanism, especially in deeper atmospheric layers (Simić et al, 2006;Hamdi et al, 2008;Dufour et al, 2011;Hamdi et al, 2014;Dimitrijević and Chougule, 2018). In order to determine chromium abundance in such stars, as well as for opacity calculations and more sophysticated stellar atmosphere modeling, we need the corresponding Stark broadening data.…”

Stark Broadening in Compact Stars: Xe VI Lines

“…Hamdi et al (2008) analyzed Stark broadening of Si VI spectral lines in DO white dwarf spectra and Hamdi et al (2014) Stark broadening of Ar III spectral lines in subdwarf B stars. It is shown that the influence of Stark broadening in the considered compact star spectra increases with log g and is dominant in broad atmospheric layers.…”