Chromospheric and Coronal Wave Generation in a Magnetic Flux Sheath

Abstract

Using radiation magnetohydrodynamic simulations of the solar atmospheric layers from the upper convection zone to the lower corona, we investigate the self-consistent excitation of slow magneto-acoustic body waves (slow modes) in a magnetic flux concentration. We find that the convective downdrafts in the close surroundings of a two-dimensional flux slab "pump" the plasma inside it in the downward direction. This action produces a downflow inside the flux slab, which encompasses ever higher layers, causing an upwardly propagating rarefaction wave. The slow mode, excited by the adiabatic compression of the downflow near the optical surface, travels along the magnetic field in the upward direction at the tube speed. It develops into a shock wave at chromospheric heights, where it dissipates, lifts the transition region, and produces an offspring in the form of a compressive wave that propagates further into the corona. In the wake of downflows and propagating shock waves, the atmosphere inside the flux slab in the chromosphere and higher tends to oscillate with a period of $\nu \approx 4$~mHz. We conclude that this process of "magnetic pumping" is a most plausible mechanism for the direct generation of longitudinal chromospheric and coronal compressive waves within magnetic flux concentrations, and it may provide an important heat source in the chromosphere. It may also be responsible for certain types of dynamic fibrils.

16 pages, 12 figures, accepted in ApJ

References in corpus (8)

• Dynamic Fibrils are driven by Magnetoacoustic Shocks
• High Resolution Observations and Modeling of Dynamic Fibrils
• On the prevalence of small-scale twist in the solar chromosphere and transition region
• Non-linear numerical simulations of magneto-acoustic wave propagation in small-scale flux tubes
• Dynamics of the Solar Magnetic Network. II. Heating the Magnetized Chromosphere
• Non-linear propagation of kink waves to the solar chromosphere
• Axisymmetric Modes in Magnetic Flux Tubes with Internal and External Magnetic Twist
• New analytical and numerical models of solar coronal loop: I. Application to forced vertical kink oscillations

Cited by in corpus (12)

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• High-frequency Oscillations in Small Magnetic Elements Observed with Sunrise/SuFI
• A Comprehensive Radiative Magnetohydrodynamics Simulation of Active Region Scale Flux Emergence from the Convection Zone to the Corona
• The small-scale structure of photospheric convection retrieved by a deconvolution technique applied to Hinode/SP data
• Chromospheric polarimetry through multi-line observations of the 850 nm spectral region II: A magnetic flux tube scenario
• Slow magneto-acoustic waves in simulations of a solar plage region carry enough energy to heat the chromosphere
• Finding the mechanism of wave energy flux damping in solar pores using numerical simulations
• Chromospheric polarimetry through multi-line observations of the 850 nm spectral region III: Chromospheric jets driven by twisted magnetic fields
• Synthesis of infrared Stokes spectra in an evolving solar chromospheric jet
• Internal Gravity Waves in the Magnetized Solar Atmosphere. II. Energy Transport
• Modelling the interaction of Alfvénic fluctuations with coronal mass ejections in the low solar corona