Comparative study of low-temperature opacities with GARSTEC models

TL;DR

This study compares the impact of two different low-temperature opacity datasets on stellar evolution models up to the RGB phase, finding minimal differences after calibration.

Contribution

It provides a direct comparison of low-temperature opacities from two sources within GARSTEC models, highlighting their negligible effect after calibration.

Findings

Stellar tracks are nearly unaffected by opacity choice after calibration.

Maximum temperature variation at RGB stages is 25-30 K.

Opacity differences are minor within the studied temperature range.

Abstract

We present a comparative study of the effect of low-temperature opacities on stellar models up to the Red Giant branch (RGB), computed with the GARching STellar Evolution Code. We have used two sets of low-temperature opacities; {\AE}SOPUS ({\AE}) from the University of Padova and those from the Wichita State University group (F05). In the relevant range of temperatures for this study, log \k{appa}{\AE} < log \k{appa}F 05. Therefore, to compare stellar evolutionary tracks, we performed a solar calibration of the {\alpha}mlt, for each set of low-temperature opacities. After carrying such a calibration, we find that stellar evolutionary tracks are almost unaffected by the choice of low-temperature opacities, with largest variations of 25-30 K at the latest evolutionary stages of the RGB phase.