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Star quakes : a new tool to test the properties of red giant stars
Nadège Lagarde (Institut UTINAM Observatoire de Besançon), Bossini Diego (University of Birmingham), Miglio Andrea (University of Birmingham ), Vrard Mathieu (LESIA, Observatoire de Paris), Mosser Benoit (LESIA, Observatoire de Paris)
In the context of the determination of stellar properties using asteroseismology, we study the influence of rotation and convective-core overshooting on the properties of red giant stars. We used stellar evolution models to investigate effects of these both mechanisms on the asymptotic period spacing of red-giant stars that ignite He burning in degenerate conditions (M≤2.0 Msun). We also compare the theoretical predictions with recent Kepler observations (Vrard et al 2016). We find that mixing processes have an impact on ∆∏(l=1), hence on the determination of the stellar mass when ∆∏(l=1) is used as a constraint. In the case of more evolved red-giant-branch stars and regardless of the transport processes occurring in their interiors, the observed ΔΠ1 can provide information as to their stellar luminosity, within ~ 10-20 per cent. In general, the trends of ΔΠ1 with respect to mass and metallicity that are observed in Kepler red-giant stars are well reproduced by the models.