Hyperfine Splitting in the VALD Database of Spectral-line Parameters

TL;DR

This paper enhances the VALD spectral database by incorporating hyperfine splitting data for atomic levels, enabling more accurate analysis of stellar spectra across various spectral types and wavelength ranges.

Contribution

It introduces a new ancillary database with hyperfine splitting constants for 58 isotopes, expanding the capabilities of VALD for spectral line analysis.

Findings

Hyperfine splitting affects up to 60% of ultraviolet lines and 100% of optical/infrared lines in A--M stars.

The database improves spectral analysis for different stellar types, especially in UV and optical ranges.

Laboratory data are necessary for hot O--B stars with higher ionization stages.

Abstract

The Vienna Atomic Line Database (VALD) has been supplemented with new data and new functionality -- the possibility of taking into account the effect of hyperfine splitting (HFS) of atomic levels in the analysis of line profiles. This has been done through the creation of an ancillary SQL database with the HFS constants for atomic levels of 58 isotopes of 30 neutral and singly-ionized atoms. The completeness of the collected data and new opportunities for studies of stars of various spectral types is analyzed. The database enables analysis of splitting of up to 60\%\ of lines with measurable effects in the ultraviolet ($\lambda\gtrsim1000$~\AA), and up to 100\%\ of such lines in the optical and infrared ranges ($\lambda\lesssim25000$~\AA) for A--M stars. In the spectra of hot O--B stars, it is necessary to use laboratory measurements for atoms in the second and higher stages of ionization.