Optical spectroscopy of Be stars: Peak separation of Balmer emission lines

The Be stars display variable optical emission lines originating in the circumstellar disc. Here we analyse high resolution spectroscopic observations of and distance between peaks H-alpha, H-beta, H-gamma ($\Delta V_\alpha$, $\Delta V_\beta$, V_\gamma$ respectively). Combining published data, spectra from ELODIE archive (obtained period 1998 -- 2003) Rozhen 2015 2023) 93 stars, find a set relations connecting V_\beta$ V_\gamma$. They are effective for $30 \le \Delta V_\alpha 500$ km s$^{-1}$, $80 V_\beta 600$ $40 V_\gamma 300$ s$^{-1}$. new equations form $y=ax + b$ valid wider velocity range than previous studies.