A&A Supplement series, Vol. 128, March II 1998, 497-505
Received January 3; accepted August 20, 1997
I.Kh. Iliev 
, J. Budaj 
, J.
Zverko , I.S. Barzova , and J. Žižňovský
Send offprint request: J. Budaj
Astronomical Institute, Slovak Academy of Sciences,
059 60 Tatranská Lomnica, The Slovak Republic
e-mail (Internet): (budaj, zve, ziga)@ta3.sk
Institute of Astronomy, National Astronomical Observatory, P.O.B. 136,
BG-4700, Smolyan, Bulgaria
e-mail (Internet): rozhen@sm.unacs.bg
High signal-to-noise CCD spectra of three bright, long period Am binaries (HD108651, HD116657 and HD138213) have been obtained and the atmospheric abundances of identified chemical elements were studied. We found HD116657 to be a new candidate as a Li deficient, long period Am binary, in addition to 16 Ori. While HD108651 and HD116657 have pronounced Am characteristics, HD138213 is just a mild Am star.
These stars were further studied in a more general context related to the role of binarity in CP phenomenon. It was found that both Li abundance and the equivalent with ratio Ca I6718/Fe I6679 are more peculiar in systems with more pronounced eccentricities. Such behaviour is the opposite of what was previously found in Ap binaries and their anomalies. It indicates that tidal effects are of crucial importance in driving CP phenomena.
keywords: stars: chemically peculiar -- stars: abundances -- stars: individual: HD108651, HD116657, HD138213 -- binaries: general