On the Heating of the Solar Corona and the Acceleration of the Low-Speed Solar Wind by Acoustic Waves Generated in the Corona

We investigate possibilities of solar coronal heating by acoustic waves generated not in the photosphere but in the corona, focusing on heating in the mid- to low-latitude corona, where the low-speed wind is expected to come from. Acoustic waves of period τ~100 s are triggered by chromospheric reconnection, one model of small-scale magnetic reconnection events recently proposed by Sturrock. These waves, having a finite amplitude, eventually form shocks to shape sawtooth waves (N-waves) and directly heat the surrounding corona by dissipation of their wave energy. Outward propagation of the N-waves is treated based on weak-shock theory, so that the heating rate can be evaluated consistently with physical properties of the background coronal plasma without setting a dissipation length in an ad hoc manner. We construct coronal structures from the upper chromosphere to outside 1 AU for various acoustic wave inputs, with a range of energy flux of F_w,0=(1-20)×10⁵ ergs cm^-2 s^-1 and a period of τ=60-300 s. The heating by the N-wave dissipation works effectively in the inner corona, and we find that waves of F_w,0>=2×10⁵ ergs cm^-2 s^-1 and τ>=60 s could maintain the peak coronal temperature, T_max>10⁶ K. The model could also reproduce the density profile observed in the streamer region. However, due to its short dissipation length, the location of T_max is closer to the surface than in observation, and the resulting flow velocity of the solar wind is lower than the observed profile of the low-speed wind. Cooperation with other heating and acceleration sources with larger dissipation lengths are inevitably needed to reproduce the real solar corona.