Properties of the solar granulation obtained from the inversion of low spatial resolution spectra

The spectra of cool stars are rich in information on elemental abundances, convection and non-thermal heating. Extracting this information is by no me ans straight forward, however. Here we demonstrate that an inversion techni que may not only provide the stratification of the classical parameters des cribing a model atmosphere, but can also determine the properties of convec tion at the stellar surface. The inversion technique is applied to spectra of photospheric lines, one recorded at the quiet solar disk center, the oth er integrated over the whole disk. We find that a model based on a single p lane-parallel atmosphere gives unsatisfactory fits to the spectral lines an d suffers from considerable uncertainties in the derived temperature strati fication. Also, the elemental abundances returned by the inversion are not particularly reliable. These problems are greatly reduced if two atmospheri c components, corresponding to granular up and downflows are allowed for. T he best results are obtained if the line profiles and bisectors of a neutra l and ionized species are fit and the results are constrained using a simpl e mass conservation scheme. We find that inversions based on two- and three -component models of disk-integrated spectra give similar results to invers ions of disk-center observations, although with somewhat lower accuracy. Th is similarity is promising for future applications of line profile inversio ns to the study of late-type stars and in particular their convection.