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arXiv · 0910.1597

Solar Magnetic Field Signatures in Helioseismic Splitting Coefficients

Charles S. Baldner·H. M. Antia·Sarbani Basu·T. P. Larson
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Abstract

Normal modes of oscillation of the Sun are useful probes of the solar interior. In this work, we use the even-order splitting coefficients to study the evolution of magnetic fields in the convection zone over solar cycle 23, assuming that the frequency splitting is only due to rotation and a large scale magnetic field. We find that the data are best fit by a combination of a poloidal field and a double-peaked near-surface toroidal field. The toroidal fields are centered at r=0.999R_solar and r=0.996R_solar and are confined to the near-surface layers. The poloidal field is a dipole field. The peak strength of the poloidal field is 124 +/- 17G. The toroidal field peaks at 380 +/- 30G and 1.4 +/- 0.2kG for the shallower and deeper fields respectively. The field strengths are highly correlated with surface activity. The toroidal field strength shows a hysteresis-like effect when compared to the global 10.7 cm radio flux. The poloidal field strength shows evidence of saturation at high activity.

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Charles S. Baldner, H. M. Antia, Sarbani Basu, T. P. Larson. 2009-10-08. Solar Magnetic Field Signatures in Helioseismic Splitting Coefficients. https://doi.org/10.1088/0004-637x%2F705%2F2%2F1704

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