Improved Stark Broadened Profiles for Neutral Helium Lines Using Computer Simulations

TL;DR

This paper develops an updated grid of Stark-broadened neutral helium line profiles using computer simulations, covering a wide range of densities and temperatures, and compares these with previous models to improve astrophysical spectral analysis.

Contribution

It introduces a new, simulation-based grid of helium line profiles that incorporates recent physical insights, improving upon semi-analytical models for astrophysical applications.

Findings

New line profile grid covers densities 10^14 to 6x10^17 cm^-3 and temperatures 10,000 to 40,000 K.

Comparison shows significant corrections to previous semi-analytical profiles.

Profiles impact the analysis of helium-rich stars and white dwarf atmospheres.

Abstract

The study of Stark broadening of neutral helium lines, despite significant advances over recent decades, has not led to updated large grids of helium line profiles relevant to the spectroscopic study of helium-rich stars. While the semi-analytical approach based on the standard Stark broadening theory is efficient for generating such grids, it presents challenges in incorporating additional physical effects into the model. Motivated by recent studies that highlight potential issues with line profiles in the context of white dwarf stars, this paper leverages advances in computer simulations to create a new grid of line profiles for 13 neutral helium lines in the optical range. These profiles cover densities ranging from 10^14 to 6 x 10^17 cm^-3 and temperatures from 10,000 K to 40,000 K, with the exception of the narrower He I 4713 line, for which the profile grid begins at 10^15.5 cm^-3. The primary goal of this research is to present the new grid and compare it with both the semi-analytical approach and other simulation results. By doing so, corrections to the previous grid will be explored, providing a foundation for future studies that utilize this updated grid. We also examine the impact of these new profiles on the determination of physical parameters for a range of astrophysical objects, including DB white dwarfs and other helium-rich stars.