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MSI Workshop. Photospheric MHD simulation of solar pores. Robert Cameron Alexander Vögler Vasily Zakharov Manfred Schüssler Max-Planck-Institut für Sonnensystemforschung Katlenburg-Lindau, Germany. Equations. Compressible non-ideal MHD with radiation
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MSI Workshop Photospheric MHD simulation of solar pores Robert Cameron Alexander Vögler Vasily Zakharov Manfred Schüssler Max-Planck-Institut für Sonnensystemforschung Katlenburg-Lindau, Germany
Equations • Compressible non-ideal MHD with radiation • Momentum equation, Lorentz force and artificial viscosity • Continuity equation • Induction equation, with proper diffusion • Energy equation, with non-gray radiation • Equation of state, including partial ionization
Setup • Box size 288 x 288 x 100 grid points • Boundary conditions Vertical field above box OR Potential field above box • Initial Conditions Two total fluxes considered (today only larger case considered). Simulate 2-D to get near equilibrium then create 3-D initial condition. Injection of some opposite polarity flux in some runs 1.4 Mm 12 Mm 12 Mm
The MURaM code University of Chicago: Basic MHD code MPS (Alexander Vögler): Radiative Transfer Hyper Diffusivities • Finite Differences • Fixed, uniformly spaced mesh (288 x 288 x 100) • Forth order in space • Runge-Kutta • Hyper Diffusivities • Short Characteristic method for radiation
Results Intensity |B| (tau=1) Bvert (tau=1) Uvert (tau=1)
Vertical Structure Pore simulation Quiet Sun Simulation Observed pores (Sutterlin) Simulations
Vertical Structure 2: Energy transport Temperature Vertical Field Z=-240 Z=-360 Z=-480
Vertical Structure 2: Energy transport Temperature at a fixed geometrical height (3 copies)
Vertical Structure 2: Energy transport log(Tau constant geometrical depth) Intensity Vertical magnetic field (Tau=1 surface)
Slice Temperature contours Temperature Tau=1 level Magnetic field lines Magnetic energy Tau=1 level
Radial Structure TAU=1 TAU=0.1
Radial Structure TAU=1 TAU=0.1
Topology From bottom to top From top to bottom Inverse U loops
Evolution Average field strength (depends on how pore is defined) Flux decay from pore
Evolution Intensity v size
A view from the side 500nm =0.7 0.5 0.2
Main conclusions • Thermal properties of pore similar to observations • Magnetic fields and magnetic field gradient sensitive to definition of the pores edge. • Energy transport involves plumes which are dark at surface (?) • Topology is becoming interesting (but the pore is still small). • Side views have reasonable enhancements, but is quite smooth.