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Symbiotic stars often exhibit broad wings around Balmer emission lines, whoseorigin is still controversial. We present the high resolution spectra of the Stype symbiotic stars Z Andromedae and AG Draconis obtained with the ESPaDOnSand the 3.6 m Canada France Hawaii Telescope to investigate the broad wingsaround H$\alpha$ and H$\beta$. When H$\alpha$ and H$\beta$ lines areoverplotted in the Doppler space, it is noted that H$\alpha$ profiles areoverall broader than H$\beta$ in these two objects. Adopting a Monte Carloapproach, we consider the formation of broad wings of H$\alpha$ and H$\beta$through Raman scattering of far UV radiation around Ly$\beta$ and Ly$\gamma$and Thomson scattering by free electrons. Raman scattering wings are simulatedby choosing an H I region with a neutral hydrogen column density $N_{HI}$ and acovering factor $CF$. For Thomson wings, the ionized scattering region isassumed to cover fully the Balmer emission nebula and is characterized by theelectron temperature $T_e$ and the electron column density $N_e$. Thomson wingsof H$\alpha$ and H$\beta$ have the same width that is proportional to$T_e^{1/2}$. However, Raman wings of H$\alpha$ are overall three times widerthan H$\beta$ counterparts, which is attributed to different cross section forLy$\beta$ and Ly$\gamma$. Normalized to have the same peak values and presentedin the Doppler factor space. H$\alpha$ wings of Z And and AG Dra are observedto be significantly wider than H$\beta$ counterpart, favoring the Ramanscattering origin of broad Balmer wings.

Broad Wings around H$\alpha$ and H$\beta$ in the Two S-Type Symbiotic Stars Z Andromedae and AG Draconis