# Evolutionary states of red-giant stars from grid-based modelling

## TL;DR

This paper introduces a grid-based asteroseismic modelling method to accurately determine whether red-giant stars are in the helium-core-burning phase or just burning hydrogen, overcoming observational challenges.

## Contribution

The study develops a new approach combining global asteroseismic properties with stellar parameters to identify red-giant evolutionary states from limited data.

## Key findings

- Effective in classifying red-giant evolutionary phases
- Applicable to limited timeseries data
- Achieves high accuracy with minimal misclassification

## Abstract

From its surface properties it can be difficult to determine whether a red-giant star is in its helium-core-burning phase or only burning hydrogen in a shell around an inert helium core. Stars in either of these stages can have similar effective temperatures, radii and hence luminosities, i.e. they can be located at the same position in the Hertzsprung-Russell diagram. Asteroseismology -- the study of the internal structure of stars through their global oscillations -- can provide the necessary additional constraints to determine the evolutionary states of red-giant stars. Here, we present a method that uses grid-based modelling based on global asteroseismic properties ($\nu_{\rm max}$, frequency of maximum oscillation power; and $\Delta\nu$, frequency spacing between modes of the same degree and consecutive radial orders) as well as effective temperature and metallicity to determine the evolutionary phases. This method is applicable even to timeseries data of limited length, although with a small fraction of miss-classifications.