Simulations of Alfven wave driving of the solar chromosphere - efficient heating and spicule launching

Abstract

Two of the central problems in our understanding of the solar chromosphere are how the upper chromosphere is heated and what drives spicules. Estimates of the required chromospheric heating, based on radiative and conductive losses suggest a rate of $\sim 0.1\mathrm{erg}\mathrm{c}{\mathrm{m}}^{-3}{\mathrm{s}}^{-1}$ in the lower chromosphere dropping to $\sim 10^{-3}\mathrm{erg}\mathrm{c}{\mathrm{m}}^{-3}{\mathrm{s}}^{-1}$ in the upper chromosphere (\citet{Avrett1981}). The chromosphere is also permeated by spicules, higher density plasma from the lower atmosphere propelled upwards at speeds of $\sim 10-20\mathrm{km}{\mathrm{s}}^{-1}$, for so called Type-I spicules (\citet{Pereira2012,Zhang2012}), reaching heights of $\sim 3000-5000\mathrm{km}$ above the photosphere. A clearer understanding of chromospheric dynamics, its heating and the formation of spicules, is thus of central importance to solar atmospheric science. For over thirty years it has been proposed that photospheric driving of MHD waves may be responsible for both heating and spicule formation. This paper presents results from a high-resolution MHD treatment of photospheric driven Alfvén and kink waves propagating upwards into an expanding flux tube embedded in a model chromospheric atmosphere. We show that the ponderomotive coupling from Alfvén and kink waves into slow modes generates shocks which both heat the upper chromosphere and drive spicules. These simulations show that wave driving of the solar chromosphere can give a local heating rate which matches observations and drive spicules consistent with Type-I observations all within a single coherent model.

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Cited by in corpus (13)

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• Partially Ionized Plasmas in Astrophysics
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• Energy transport and heating by torsional Alfvén waves propagating from the photosphere to the corona in the quiet Sun
• A Hydrodynamic Model of Alfvénic Wave Heating in a Coronal Loop and its Chromospheric Footpoints
• The Onset of 3D Magnetic Reconnection and Heating in the Solar Corona
• Simulation of Alfven wave propagation in magnetic chromosphere with radiative loss: effects of non-linear mode coupling on chromospheric heating
• Fast magnetic wave could heat the solar low-beta chromosphere
• Shocks and instabilities in the partially ionised solar atmosphere
• Coronal Properties of Low-mass Population III Stars and the Radiative Feedback in the Early Universe
• Time-Dependent Two-Fluid Magnetohydrodynamic Model and Simulation of the Chromosphere
• A new view of the solar interface region from the Interface Region Imaging Spectrograph (IRIS)