Solar magnetic field signatures in helioseismic splitting coefficients

Baldner, Charles S. ; Antia, H. M. ; Basu, Sarbani ; Larson, Timothy P. (2009) Solar magnetic field signatures in helioseismic splitting coefficients Astrophysical Journal, 705 (2). pp. 1704-1713. ISSN 0004-637X

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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 r0=0.999 R and r=0.996 R and are confined to the near-surface layers. The poloidal field is a dipole field. The peak strength of the poloidal field is 124 ± 17 G. The toroidal field peaks at 380 ± 30 G and 1.4 ± 0.2 kG 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.

Item Type:Article
Source:Copyright of this article belongs to American Astronomical Society.
Keywords:Sun: Activity; Sun: Helioseismology; Sun: Magnetic Fields
ID Code:12370
Deposited On:10 Nov 2010 06:20
Last Modified:16 May 2016 21:43

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