Non-linear numerical simulations of magneto-acoustic wave propagation in small-scale flux tubes

Abstract

We present results of non-linear, 2D, numerical simulations of magneto-acoustic wave propagation in the photosphere and chromosphere of small-scale flux tubes with internal structure. Waves with realistic periods of three to five minutes are studied, after applying horizontal and vertical oscillatory perturbations to the equilibrium model. Spurious reflections of shock waves from the upper boundary are minimized thanks to a special boundary condition. This has allowed us to increase the duration of the simulations and to make it long enough to perform a statistical analysis of oscillations. The simulations show that deep horizontal motions of the flux tube generate a slow (magnetic) mode and a surface mode. These modes are efficiently transformed into a slow (acoustic) mode in the vA < cS atmosphere. The slow (acoustic) mode propagates vertically along the field lines, forms shocks and remains always within the flux tube. It might deposit effectively the energy of the driver into the chromosphere. When the driver oscillates with a high frequency, above the cut-off, non-linear wave propagation occurs with the same dominant driver period at all heights. At low frequencies, below the cut-off, the dominant period of oscillations changes with height from that of the driver in the photosphere to its first harmonic (half period) in the chromosphere. Depending on the period and on the type of the driver, different shock patterns are observed.

22 pages 6 color figures, submitted to Solar Physics, proceeding of SOHO 19/ GONG 2007 meeting, Melbourne, Australia

References in corpus (2)

• Solar Atmospheric Oscillations and the Chromospheric Magnetic Topology
• Observations of Running Waves in a Sunspot Chromosphere

Cited by in corpus (22)

• A global view of velocity fluctuations in the corona below 1.3 $R_{\odot }$ with CoMP
• Rayleigh-Taylor instability in prominences from numerical simulations including partial ionization effects
• Waves in the lower solar atmosphere: the dawn of next-generation solar telescopes
• An Inside Look at Sunspot Oscillations with Higher Azimuthal Wavenumbers
• High-frequency Oscillations in Small Magnetic Elements Observed with Sunrise/SuFI
• Multifluid modeling of magnetosonic wave propagation in the solar chromosphere -- effects of impact ionization and radiative recombination
• Non-linear propagation of kink waves to the solar chromosphere
• Observational evidence for buffeting induced kink waves in solar magnetic elements
• The solar chromosphere at millimetre and ultraviolet wavelengths. I. Radiation temperatures and a detailed comparison
• Wave modes excited by photospheric p-modes and mode conversion in a multi-loop system
• Chromospheric and Coronal Wave Generation in a Magnetic Flux Sheath
• Resonant absorption in expanding coronal magnetic flux tubes with uniform density
• Coalescence Instability in Chromospheric Partially Ionised Plasmas
• A Fixed-point Scheme for the Numerical Construction of Magnetohydrostatic Atmospheres in Three Dimensions
• The energy of waves in the photosphere and lower chromosphere: II. Intensity statistics
• Transmission and conversion of magnetoacoustic waves on the magnetic canopy in a quiet Sun region
• Spectropolarimetric Fluctuations in a Sunspot Chromosphere
• Oscillatory behavior in the quiet Sun observed with the New Solar Telescope
• Collisional ionisation and recombination effects on coalescence instability in chromospheric partially ionised plasmas
• Evaluation of the capability of local helioseismology to discern between monolithic and spaghetti sunspot models
• 3D Numerical Simulations of f-Mode Propagation Through Magnetic Flux Tubes
• Large-amplitude longitudinal oscillations in solar prominences simulated with different resolutions