2005A&A...435.1191D

Using the semiclassical perturbation method, electron-, proton-, and ionized helium-impact line widths and shifts for the nine CrI spectral lines from the 4p⁷P⁰-4d⁷D multiplet were calculated for a perturber density of 10¹⁴cm^–3 and for temperatures T=2500-50000K. The results were used to investigate the influence of Stark broadening effect in the Cr-rich Ap star β CrB atmosphere on line shapes of these lines. It was found that the contribution of proton and HeII collisions to the line width and shift is significant and comparable, and is sometimes even larger than electron-impact contribution depending of the electron temperature. Moreover, not only the Stark line width, but also the Stark shift may contribute to the blue as well as to the red asymmetry of the same line depending on the electron-, proton-, and HeII density in stellar atmosphere. The results were used to investigate the influence of Stark broadening effect on CrI line shapes in the atmosphere of the Cr-rich Ap star β CrB.