Stark widths for prospective search of Tc VI lines in white dwarf atmospheres

ABSTRACT Recently, several trans-iron group elements from Zn ($Z=30$) to Ba ($Z=56$) have been discovered in hot white dwarfs. This discovery suggests possible existence of the element technetium ($Z=43$), although it is not yet possible to confirm this due to the lack of atomic and Stark broadening data for elements beyond Tc II. Theoretical evaluations and measurements of atomic and Stark broadening data are a prerequisites for stellar-atmosphere modelling, which is a tool for the determination of the photospheric abundance of these species, for example, atomic data such as energy levels and oscillator strengths are used to estimate the minimum level of abundance for which the element technetium could be detected. In an effort to contribute to providing these data, we calculate for the first time the Stark broadening data for 10 spectral lines of the Tc VI ion using our quantum mechanical and semiclassical methods. Along with line broadening data, we calculate also the wavelengths, oscillator strengths, radiative decay rates of some optically allowed transitions, and collision strengths using the codes superstructure and distorted wave and compare them to the results of the autostructure code. Obtained data will be also implemented into the database of Stark broadening parameters STARK-B.