1997A&A...326..655B

We reveal sufficient evidences that for Am binaries the metallicity might depend on their orbital periods, P_orb, rather than on vsini. In particular, δm₁ index seems to decrease with increasing orbital period up to at least P_orb≃50d, probably even up to P_orb≃200d. This gives further support to our "tidal mixing + stabilization" hypothesis formulated in Part I. Moreover, while the most metallic Am stars seem to have rather large periods the slowest rotators are found to exhibit substantially shorter P_orb. A questioning eye is thus cast on the generally adopted view that Am peculiarity is caused by a suppressed rotationally induced mixing in slowly rotating `single' stars. The observed anticorrelation between rotation and metallicity may have also other than the `textbook' explanation, namely being the result of the correlation between metallicity and orbital period, as the majority of Am binaries are possibly synchronized. We further argue that there is a tendency in Am binaries towards pseudo-synchronization up to P_orb≃35d. This has, however, no serious impact on our conclusions from Part I; on the contrary, they still hold even if this effect is taken into account.