Granulation across the HR diagram

TL;DR

This study uses high-resolution spectra of stars across the HR diagram to test and validate advanced hydrodynamic models of stellar surface convection, revealing their strengths and limitations.

Contribution

It provides the first comprehensive validation of hydrodynamic stellar atmosphere models across various stellar types using ultra-high quality spectral data.

Findings

Validation of model predictions for line bisectors and wavelength shifts

Identification of limitations in current hydrodynamic models

Enhanced understanding of stellar surface convection processes

Abstract

We have obtained ultra-high quality spectra (R=180,000; S/N>300) with unprecedented wavelength coverage (4400 to 7400 A) for a number of stars covering most of the HR diagram in order to test the predictions of models of stellar surface convection. Line bisectors and core wavelength shifts are both measured and modeled, allowing us to validate and/or reveal the limitations of state-of-the-art hydrodynamic model atmospheres of different stellar parameters. We show the status of our project and preliminary results.