Astron. Astrophys. 326, 655-661 (1997)
On the nature of the Am phenomenon or on a stabilization
and the tidal mixing in binaries
II. Metallicity and pseudo-synchronization
Astronomical Institute, Slovak Academy of Sciences, 059
60 Tatranská Lomnica, The Slovak Republic (firstname.lastname@example.org)
Received 4 July 1996 / Accepted 12 May 1997
We reveal sufficient evidences that for Am binaries the metallicity
might depend on their orbital periods,
, rather than on
. In particular,
index seems to decrease with increasing orbital
period up to at least
, probably even up to
. 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
. 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
. 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.
Key words: stars: chemically peculiarbinaries:
© European Southern Observatory (ESO) 1997
Online publication: October 15, 1997