Z-scaling of line widths for Be-like ions using quantum mechanical calculations

We investigate the scaling of Stark line width with the spectroscopic charge Z along the beryllium-like isoelectronic sequence, ranging from C iii to Ar xv. The calculations are performed using our quantum mechanical formalism, which provides a rigorous treatment of the collision processes in multicharged ions. Stark widths are calculated at an electron density of 1017 cm−3 and for a wide range of electron temperatures (T = 104 to 106 K). By utilizing detailed quantum results for the ions C iii (Z = 3) through Ne vii (Z = 7), Si xi (Z = 11) and the highly charged Ar xv (Z = 15), we establish a linear relationship between the Stark width and the logarithm of the spectroscopic charge, expressed as log10[W(s−1)] = a + blog10(Z). The fitting coefficients a and b are provided for each considered temperature, facilitating the interpolation of data across the sequence. We demonstrate that this scaling law allows for a consistent estimation of Stark broadening parameters for the intermediate ions—Na viii, Mg ix, Al x, P xii, S xiii, and Cl xiv—confirming that these interpolated values remain in strict alignment with the systematic Z-scaling trends established by our quantum mechanical calculations, thereby bypassing the need for computationally intensive full-scale treatments. These results are of significant value for the modelling of stellar atmospheres, particularly for hot stars and white dwarfs, and contribute to the expansion of high-precision atomic databases such as STARK-B.