Extracting the excitation function of solar oscillations by means of deconvolution

Acoustic oscillations normally are excited by continuous convective motion. Because of the turbulent nature of convection, the low-degree modes generated by convection should be uncorrelated. However, in earlier studies (e.g., Baudin, Gabriel, Gibert, Palle & Regulo (1996), Foglizzo (1998)), a possible correlation between different modes was noticed in the IPHIR data. It was suspected that there might have been occasional solar activities as excitation sources during this period of time. However, the existence of this kind of excitation mechanism was not directly shown. The goal of this study is to reconstruct the forcing function that causes the excitation. In typical observations of solar oscillations, the sampling time (around 1 minute) is insufficient to resolve the excitation resulting from continuous convection. Thus, only infrequent excitation caused by irregular events can be revealed. Therefore, this method can become a tool to investigate infrequent solar events. The testing results from artificial signals have been reported in our previous paper (Lin & Dappen, 2000). Here. we present our current status of the application to four sets of real signals: SOI/MDI, VIRGO, GOLF and IPHIR.