Properties of the ionisation glitch. II. Seimic signature of the structural perturbation

In the present paper, we aim to constrain properties of ionisation region in a star from oscillation frequency variation (a so-called glitch) caused by rapid structural variations this very region. particular, seek avoid use calibration based on stellar models thus providing truly independent estimate these properties. These include both helium abundance and other physical quantities that can have significant impact frequencies such as electronic degeneracy parameter or extent Taking starting point our first applied perturbations zone wave equation for radial oscillations an isentropic The resulting glitch model is able exploit information contained fast but also slow trend accompanying hydrogen. This directly be expressed terms parameters related respectively abundance, Using Bayesian inference, show substantial recovery at origin possible. A between found exist, which particularly affects estimate. Extending method cases where subject contamination (e.g. surface effects), noted importance associated with hydrogen ionisation. We propose using Gaussian process disentangle effects.