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

From its surface properties it can be di ffi cult 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 e ff ective 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 ( ν max , frequency of maximum oscillation power; and ∆ ν , frequency spacing between modes of the same degree and consecutive radial orders) as well as e ff ective 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