3D spectral synthesis and rotational line broadening

TL;DR

This paper introduces a new method for accurately modeling rotational line broadening in 3D stellar atmosphere spectral synthesis, even with limited angular resolution of the radiation field.

Contribution

It develops a novel approach combining analytical and numerical techniques to improve rotational broadening treatment in 3D spectral synthesis models.

Findings

Method outperforms previous procedures in accuracy.

Applicable to both rigid and differential rotation.

Enhances spectral modeling with limited limb-angle data.

Abstract

Spectral synthesis calculations based on three-dimensional stellar atmosphere models are limited by the affordable angular resolution of the radiation field. This hampers an accurate treatment of rotational line broadening. We aim to find a treatment of rotational broadening of a spherical star when the radiation field is only available at a modest number of limb-angles. We apply a combination of analytical considerations of the line-broadening process and numerical tests. We obtain a method which is closely related to classical flux convolution and which performs noticeably better than a previously suggested procedure. It can be applied to rigid as well as differential rotation.