While sunspots are easily observed at the solar surface, determining their subsurface structure is not trivial. There are two main hypotheses for the subsurface structure of sunspots: the monolithic model and the cluster model. Local helioseismology is the only means by which we can investigate subphotospheric structure. However, as current linear inversion techniques do not yet allow helioseis...

A numerical model of axisymmetric convection in the presence of a vertical magnetic flux bundle and rotation about the axis is presented. The model contains a compressible plasma described by the nonlinear MHD equations, with density and temperature gradients simulating the upper layer of the sun’s convection zone. The solutions exhibit a central magnetic flux tube in a cylindrical numerical do...

The authors show how the influence of extrinsic random signals depends on the noise structure of these signals. They present an experiment on a coordination game in which extrinsic random signals may generate sunspot equilibria. They measure how these signals affect behavior. Sunspot equilibria emerge naturally if there are salient public signals. Highly correlated private signals may also caus...

In order to study umbral oscillations, running penumbral waves and the relationship between them, we analyzed CCD, high resolution, sunspot observations obtained at center and the wings of the Hα line and the Fe I 5576 Å line. The UBF filter was used in order to produce high cadence sequences of filtergrams. Images were processed to remove the sharp intensity gradient between the umbra and the ...