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Helioseismic probing of the subsurface structure of sunspots

Published online by Cambridge University Press:  26 August 2011

A.D. Crouch ,
A.C. Birch ,
D.C. Braun  and
C.T.M. Clack
A.D. Crouch
Affiliation:
NorthWest Research Associates, Colorado Research Associates Division 3380 Mitchell Lane, Boulder, CO
A.C. Birch
Affiliation:
NorthWest Research Associates, Colorado Research Associates Division 3380 Mitchell Lane, Boulder, CO
D.C. Braun
Affiliation:
NorthWest Research Associates, Colorado Research Associates Division 3380 Mitchell Lane, Boulder, CO
C.T.M. Clack
Affiliation:
NorthWest Research Associates, Colorado Research Associates Division 3380 Mitchell Lane, Boulder, CO
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Abstract

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We discuss recent progress in the helioseismic probing of the subsurface structure of solar magnetic regions. To simulate the interaction of helioseismic waves with magnetic fields and thermal perturbations we use a simple model that is translation invariant in the horizontal directions, has a realistic stratification in the vertical direction, and has physically consistent boundary conditions for the waves at the upper and lower boundaries of the computational domain. Using this model we generate synthetic helioseismic data and subsequently measure time-distance travel times. We evaluate a model for the wave-speed perturbation below sunspots that replaces the sound speed in a non-magnetic model by the fast-mode speed from a magnetic model; our results indicate that this approach is unlikely to be useful in modeling wave-speed perturbations in sunspots. We develop and test an inversion algorithm for inferring the sound-speed perturbation in magnetic regions. We show that this algorithm retrieves the correct sound-speed perturbation only when the sensitivity kernels employed account for the effects of the magnetic field on the waves and the subsurface structure.

Keywords

Sun: helioseismologySun: magnetic fieldssunspots
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 6 , Symposium S273: The Physics of Sun and Star Spots , August 2010 , pp. 384 - 388
Copyright
Copyright © International Astronomical Union 2011

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