Determining rotational and macroturbulent velocities of cool magnetic giant stars

TL;DR

This paper introduces a new spectrum synthesis method to accurately determine rotational and macroturbulent velocities in evolved M giant stars, demonstrated on the star RZ Ari.

Contribution

It presents an original spectrum synthesis technique for estimating $vsini$ and $v_{mac}$ in cool giant stars, improving measurement accuracy.

Findings

Measured $v\sin i$ = 6.0 ± 0.5 km/s for RZ Ari

Measured $v_{mac}$ = 2.0 ± 1.0 km/s for RZ Ari

Method effectively fits observed line profiles with synthetic spectra

Abstract

An original method of estimating the projected rotational velocity, $vsini$, and the macroturbulent velocity, $v_{\rm mac}$, of evolved M giant stars is presented. It is based on the use of spectrum synthesis and multi-line analysis tools. The goal is to fit the mean line profile of observations with that of synthetic spectra. The method is applied to the red giant star RZ Ari and the results $v\sin i$ = 6.0 $\pm$ 0.5 km/s and $v_{\rm mac}$ = 2.0 $\pm$ 1.0 km/s are obtained.