A photospheric bright point model

Abstract

Aims.A magneto-hydrostatic model is constructed with spectropolarimetric properties close to those of solar photospheric magnetic bright points. Methods. Results of solar radiative magneto-convection simulations are used to produce the spatial structure of the vertical component of the magnetic field. The horizontal component of magnetic field is reconstructed using the self-similarity condition, while the magneto-hydrostatic equilibrium condition is applied to the standard photospheric model with the magnetic field embedded. Partial ionisation processes are found to be necessary for reconstructing the correct temperature structure of the model. Results. The structures obtained are in good agreement with observational data. By combining the realistic structure of the magnetic field with the temperature structure of the quiet solar photosphere, the continuum formation level above the equipartition layer can be found. Preliminary results are shown of wave propagation through this magnetic structure. The observational consequences of the oscillations are examined in continuum intensity and in the Fe I 6302 Å magnetically sensitive line.

Numerical Modeling of Footpoint-Driven Magneto-Acoustic Wave Propagation in a Localized Solar Flux Tube

“…Self-similar magnetic fields have a rather simple analytical description. Compared to potential fields, the non-potential localized magnetic field configuration, which we use here, demonstrates a closer resemblance to intergranular magnetic field concentrations, observed in the solar photosphere, and to magnetic fields generated by dynamical simulations of magnetoconvection (see, e.g., Shelyag et al 2010). Finally, self-similar magnetic fields can be created with a lower expansion factor compared to their counterparts with potential fields, thus it is not necessary to use additional localized magnetic field structures or less-natural periodic boundaries to prevent the field describing a less realistic expansion.…”

Photospheric high-frequency acoustic power excess in sunspot umbra: signature of magneto-acoustic modes

“…A non-uniform non-potential self-similar static magnetic field configuration (see Schlüter and Temesváry, 1958;Deinzer, 1965;Schüssler and Rempel, 2005;Shelyag et al, 2010Shelyag et al, , 2009Fedun et al, 2011a,b,c) is implemented in half of the domain to mimic sunspot properties. The maximum vertical magnetic field strength is 3.5 kG at the level approximately corresponding to the visible solar surface.…”

“…In fact, it is argued (Moradi and Cally, 2008;Moradi et al, 2009) that, at least some of, the inconsistencies in the helioseismic analyses of sunspots (Gizon et al, 2009) are likely due to not taking these modes into account. Numerical MHD simulations are currently used to help us gain an insight into such problems (Crouch and Cally, 2003;Shelyag et al, 2007Shelyag et al, , 2009Shelyag et al, , 2010Parchevsky and Kosovichev, 2007;Cameron et al, 2008;Khomenko et al, 2009;Felipe et al, 2010). A variety of propagating and standing MHD waves (e.g.…”

Stokes Diagnostics of Magneto-Acoustic Wave Propagation in the Magnetic Network on the Sun

“…Several authors (Rosenthal et al, 2002;Bogdan et al, 2003;Cranmer and van Ballegooijen, 2005;Hasan et al, 2005;Hasan and van Ballegooijen, 2008;Khomenko, Collados, and Felipe, 2008;Vigeesh, Hasan, and Steiner, 2009;Fedun, Erdélyi, and Shelyag, 2009;Kato et al, 2011) have investigated wave phenomena in magnetically structured atmospheres. Shelyag et al (2010) constructed a photospheric bright point model and studied the observational signatures of wave propagation in them including the response in Stokes V . The effect of a direct excitation of a magnetic flux concentration by granular buffeting and the corresponding spectral signatures of wave propagation and mode coupling and mode conversion in these structures have not been studied so far.…”