ENERGY-TRANSPORT TO THE SOLAR CORONA BY MAGNETIC KINK WAVES

We show that the magnetic kink waves generated by the motions of photo spheric footpoints of the coronal flux tubes can supply adequate energ y for heating the quiet corona, provided there are occasional rapid mo tions of these footpoints as found in recent observations (Vigneau et al. 1992). Choudhuri, Auffret, & Priest (1992) modeled the solar coron a as isothermal atmosphere and showed that these rapid motions are muc h more efficient for transporting energy compared to the slow footpoin t motions taking place most of the time. We extend these calculations for a two-layer atmosphere, with the lower layer having chromospheric thickness and temperature, and the upper layer having coronal temperat ure. Even in the presence of such a temperature jump, we find that the rapid footpoint motions are still much more efficient for transportin g energy to the corona and the estimated energy flux is sufficient for quiet coronal heating, i.e., we reinforce the conclusions of Choudhur i, Auffret, & Priest (1992). In addition to presenting results for the solar corona, we discuss the general problem of the propagation of ki nk pulses in a two-layer atmosphere for different possible values of t he basic parameters. We find a fairly complicated behavior which could not be anticipated from the analysis of a pure Fourier mode. For puls es generated by rapid footpoint motions, the energy flux decreases due to reflection at the transition layer. For pulses generated by slow f ootpoint motions, however, the behavior of the system is governed by m odes, which are evanescent in the lower layer, but can tunnel through it. The energy flux carried by such pulses can actually increase when there is a temperature jump in the atmosphere.