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Numerical simulation of interaction of MHD waves with magnetostatic models of sunspots
|Solar and stellar modelling|
|Auteur(s) supplémentaire(s)||A.G. Kosovichev(1), E.V. Khomenko(2,3), V.L. Olshevsky(3), M. Collados(2), J. Zhao(1)|
|Institution(s) supplémentaire(s)||(1) Stanford University, Stanford, USA; (2) Instituto de Astrophysica de Canarias, Tenerife, Spain; (3) Main Astrophysical Observatory, Kyiv, Ukraine|
|We present results of numerical 3D MHD simulations of propagation of|
linearized MHD waves in two different magnetostatic sunspot models
(referred to as "deep" and "shallow" models), and investigate the
interaction separately for p- and f-modes. Horizontal variations
of the background sound speed in the "deep" model are significant
at any depth and negligible in the "shallow" model below 2 Mm.
We compare wave perturbations of the density, vertical velocity,
and z-component of magnetic field at the level of fixed optical
depth (log tau = -1). Results show that the behavior of waves
in these two models is significantly different.
For the "deep" model the amplitude of perturbation of vertical
velocity decreases inside the the region with strong magnetic field.
For the "shallow" model we observe opposite effect. This behavior can be
used as an observational test of the magnetostatic models of sunspots.
The comparison with the observed behavior of the waveforms extracted
from observations (Zhao et al 2010) shows that the "deep" sunspot
model is in better agreement with the observational data.