Discovery of 17 new sharp-lined Ap stars with magnetically resolved lines

TL;DR

This study reports the discovery of 17 new magnetic Ap stars with spectroscopically resolved Zeeman lines, expanding understanding of stellar magnetism and chemical peculiarities in A-type stars through high-resolution spectroscopy.

Contribution

The paper presents the first uniform high-resolution spectroscopic survey of Ap stars in the southern hemisphere, identifying 17 new magnetic Ap stars with resolved Zeeman components.

Findings

Discovered 17 new magnetic Ap stars with magnetic fields from 3 to 30 kG.

Identified a double-lined Ap binary with a magnetic component.

Found a peculiar A star with variable abundances.

Abstract

Chemically peculiar A stars (Ap) are extreme examples of the interaction of atomic element diffusion processes with magnetic fields in stellar atmospheres. The rapidly oscillating Ap stars provide a means for studying these processes in 3D and are at the same time important for studying the pulsation excitation mechanism in A stars. As part of the first comprehensive, uniform, high resolution spectroscopic survey of Ap stars, which we are conducting in the southern hemisphere with the Michigan Spectral Catalogues as the basis of target selection, we report here the discovery of 17 new magnetic Ap stars having spectroscopically resolved Zeeman components from which we derive magnetic field moduli in the range 3 - 30 kG. Among these are 1) the current second-strongest known magnetic A star, 2) a double-lined Ap binary with a magnetic component and 3) an A star with particularly peculiar and variable abundances. Polarimetry of these stars is needed to constrain their field geometries and to determine their rotation periods. We have also obtained an additional measurement of the magnetic field of the Ap star HD 92499.