Correlation between velocity separation of maser lines and period of associated star

We found the velocity separations of both OH and SiO maser lines are strongly correlated with the period of the associated variable star and this lends support to the model of expanding shell for masers. Using our statistical result, we calculated the rate of mass loss as caused by the driving of radiation pressure and our results are in agreement with observations. The variation of flow velocity with radial distance we derived predicts a position for the SiO shell that agrees with previous estimates based on independent, astrophysical considerations, and that could be checked by future microwave observations.