Predicted masses of Gal. Cepheids from Gaia

On the basis of recently computed nonlinear convective pulsation models of Galactic Cepheids, spanning wide ranges of input stellar parameters, we derive theoretical mass-dependent Period-Wesenheit relations in the Gaia bands, namely, G, G_BP_, and G_BR_, that are found to be almost independent of the assumed efficiency of superadiabatic convection. The application to a selected subsample of the Gaia Data Release 2 Galactic Cepheids database allows us to derive mass-dependent estimates of their individual distances.

By imposing their match with the astrometric values inferred from Gaia, we are able to evaluate the individual mass of each pulsator. The inferred mass distribution is peaked around 5.6M_{sun}_ and 5.4M_{sun}_ for the F and FO pulsators, respectively. If the estimated Gaia parallax offset <{Delta}{omega}>=0.046mas is applied to Gaia parallaxes before imposing their coincidence with the theoretical ones, the inferred mass distribution is found to shift toward lower masses, namely, ~5.2M_{sun}_ and 5.1M_{sun}_ for the F and FO pulsators, respectively.