Diagnostics of the Internal Structure of Stars using the Differential Response Technique

We address the problem of the diagnosing the deep interior structure of stars using acoustic p-modes, and investigate the diagnostic capabilities of two complementary approaches both based on the differential response technique (Vorontsov, 1998): (a) direct calibration using a grid of evolutionary stellar models, and (b) linear and non-linear (with consecutive linearisations) inversion of low-degree frequencies. We apply this analysis to the frequencies of a model of an old 0.8M star, and to the solar frequencies obtained from BiSON measurements, using a 2-D grid of reference models of different mass and age. We explore the convergence and stability of the asteroseismic inversion, performed with the adaptive regularisation technique of Strakhov and Vorontsov (2001).