Evolutionary states of red-giants stars: how to obtained them from “short” time series data from K2 and Tess
Saskia Hekker (Max Planck Institute for Solar System Research), S. Basu (Yale University), Y. Elsworth (University of Birmingham)

The long (~4 yrs) nearly-uninterrupted time series data obtained by the Kepler satellite during its nominal mission have revealed unprecedented features in the oscillation spectra of red-giant stars. Among these are the mixed-gravity-pressure modes, which probe both the inner as well as the outer parts of the star. These modes provide information from the stellar core making it possible to determine whether a star is in a state before or after the onset of Helium burning. Long time series data of at least hundred(s) of days are necessary to resolve the mixed modes. Hence for red-giants observed with the K2 mission and a large fraction of stars observed with the TESS satellite this will not be feasible. Here we present another way to determine evolutionary states of red-giant stars, which do not require the detection of mixed modes.