Be stars in the exofield of CoRoT. III.

They enabled to determine: i) stellar masses which are in agreement with those measured in detached binary systems; ii) spectroscopic distances that agree with the GAIA parallaxes; iii) centrifugal/gravity ~0.6-0.7 equatorial force ratios which indicate that our Be stars are under-critical rotators. The study of the Balmer Halpha, Hgamma and Hdelta emission lines produced: 1) extents of the circumstellar disc (CD) emitting regions that agree with the interferometric inferences in other Be stars; 2) R-dependent exponents n(R)=ln[rho(R)/rho_{sun}_]/ln(R_{sun}_/R) of the CD radial density distributions; 3) CD base densities rho_{sun}_ similar to those inferred in recent studies.

The H{gamma} and H{delta} emission lines are formed in CD layers which are close to the central star. These lines produced a different value of the exponent n(R) than assumed for H{alpha}. Further detailed studies of H{gamma} and H{delta} emission lines could reveal the physical properties of regions where probably originate the viscous transport of angular momentum to the remaining CD regions.

The under-critical rotation of Be stars suggests that their huge discrete mass-ejections and concomitant non-radial pulsations might have a common origin in stellar envelope regions that become unstable to convection due to rotation. If proven that the studied Be stars are products of binary mass transfer phases, the errors induced on the estimated Teff by the presence of stripped sub-dwarf O/B companions will probably not exceed their present uncertainties.