Jonas Müller   (Germany)

 jonas.mueller @ h-its.org

Modeling the interiors of peculiar red giants

Asteroseismology allows us to constrain the interiors of stars. In red giant stars, the observable oscillation modes are mixed, i.e. they are composed of a pressure-dominated component in the convective envelope and a buoyancy-dominated component in the radiative core. The mixed modes therefore allow us to study the core of these stars. The power density spectra of some red giants have peculiar features. For a subgroup of red giants, the heights of the peaks of the dipole modes are unusually small compared to the heights of the radial modes. For another subgroup, the power density spectra appear to me messy, i.e. the signal-to-noise ratio is lower than usual, which makes it difficult to identify the modes. The cause of these peculiarities is still under debate. In my project, I aim to constrain the cause of these peculiarities using theoretical modeling. Currently, I am investigating asteroseismic signatures of an internal magnetic field, since a magnetic field in the core is a strong candidate for explaining the suppression of dipole modes.

Supervisor:    Saskia Hekker (HITS)