http://arxiv.org/abs/1310.4650
The source of the non-thermal energy required for the heating of the upper solar atmosphere to temperatures in excess of a million degrees and the acceleration of the solar wind to hundreds of kilometres per second is still unclear. One such mechanism for providing the required energy flux is incompressible torsional Alfv\’en and kink magnetohydrodynamic (MHD) waves, which are magnetically dominated waves supported by the Sun’s pervasive and complex magnetic field. In particular, propagating MHD kink waves have recently been observed to be ubiquitous throughout the solar atmosphere, but, until now, critical details of the transport of the kink wave energy throughout the Sun’s atmosphere were unclear. Here, the ubiquity of the waves is exploited for statistical studies in the highly dynamic solar chromosphere. This large-scale investigation allows for the determination of the chromospheric kink wave velocity power spectra, a missing link necessary for determining the energy transport between the photosphere and corona. Crucially, the power spectra contains evidence for horizontal photospheric motions being the main mechanism for kink wave generation in the quiescent Sun. In addition, a comparison to measured coronal power spectra is provided, revealing frequency-dependent transmission profiles suggesting there is enhanced damping of kink waves in the lower corona.
Date added: Fri, 18 Oct 13