19 - Telechronohelioseismology

Summary

Telechronohelioseismology (or time-distance helioseismology) is a new diagnostic tool for three-dimensional structures and flows in the solar interior. Along with the other methods of local-area helioseismology, the ring diagram analysis, acoustic holography and acoustic imaging, it provides unique data for understanding turbulent dynamics of magnetized solar plasma. The technique is based on measurements of travel time delays or wave-form perturbations of wave packets extracted from the stochastic field of solar oscillations. It is complementary to the standard normal mode approach which is limited to diagnostics of two-dimensional axisymmetrical structures and flows. I discuss theoretical and observational principles of the new method, and present some current results on large-scale flows around active regions, the internal structure of sunspots and the dynamics of emerging magnetic flux.

Introduction

Telechronohelioseismology (or telechronoseismology) is defined as a subdiscipline of helioseismology by Gough (1996) in his reply to criticism of the term ‘asteroseismology’ (Trimble 1995). Gough argued that, being derived from all classical Greek words, ‘thoroughbred’ telechronohelioseismology should be preferred to ‘oedipal combinations’ of Greek and Latin words. Telechronohelioseismology belongs to a new class of helioseismic measurements, broadly defined as epichorioseismology (also calledlocal-area helioseismology), which provides three-dimensional diagnostics of the solar interior.

Helioseismology is originally basedon interpretation of the frequencies of normal modes of solar oscillation.