Simulations Show that Vortex Flows could Heat the Chromosphere in Solar Plage

Abstract

The relationship between vortex flows at different spatial scales and their contribution to the energy balance in the chromosphere is not yet fully understood. We perform three-dimensional (3D) radiation-magnetohydrodynamic (MHD) simulations of a unipolar solar plage region at a spatial resolution of 10 km using the MURaM code. We use the swirling-strength criterion that mainly detects the smallest vortices present in the simulation data. We additionally degrade our simulation data to smooth-out the smaller vortices, so that also the vortices at larger spatial scales can be detected. Vortex flows at various spatial scales are found in our simulation data for different effective spatial resolutions. We conclude that the observed large vortices are likely clusters of much smaller ones that are not yet resolved by observations. We show that the vertical Poynting flux decreases rapidly with reduced effective spatial resolutions and is predominantly carried by the horizontal plasma motions rather than vertical flows. Since the small-scale horizontal motions or the smaller vortices carry most of the energy, the energy transported by vortices deduced from low resolution data is grossly underestimated. In full resolution simulation data, the Poynting flux contribution due to vortices is more than adequate to compensate for the radiative losses in plage, indicating their importance for chromospheric heating.

8 pages, 5 figures, accepted in ApJL

References in corpus (5)

• Numerical simulations of quiet Sun magnetism: On the contribution from a small-scale dynamo
• Extension of the MURaM radiative MHD code for coronal simulations
• Convectively driven vortex flows in the Sun
• Evidence of photospheric vortex flows at supergranular junctions observed by FG/SOT (Hinode)
• The horizontal internetwork magnetic field: numerical simulations in comparison to observations with Hinode

Cited by in corpus (9)

• The European Solar Telescope
• Vortex Flow Properties in Simulations of Solar Plage Region: Evidence for their role in chromospheric heating
• A solar coronal loop in a box: Energy generation and heating
• Stirring the Base of the Solar Wind: On Heat Transfer and Vortex Formation
• Three-dimensional MHD wave propagation near a coronal null point: a new wave mode decomposition approach
• Unveiling the magnetic nature of chromospheric vortices
• The importance of horizontal Poynting flux in the solar photosphere
• New approach for analysing dynamical processes on the surface of photospheric vortex tubes
• Viscous Heating and Instabilities in the Partially Ionized Solar Atmosphere