Time-Distance Measurements of Cross-Correlation Asymmetries around NOAA AR 10486

Abstract

We apply time-distance helioseismology to NOAA AR 10486 in order to examine the effect the presence of magnetic fields has on the resulting cross-correlations. Large-amplitude asymmetries between waves propagating in opposite directions are observed. The asymmetries can be attributed to suppression and absorption of seismic waves by the magnetic field. Unraveling the effects of magnetic field on the waves from the effects of sound-speed perturbations and flows is one of the major challenges facing time-distance helioseismology.