STELLAR COMPOSITIONS FROM NARROW-BAND PHOTOMETRY .5. BARIUM ABUNDANCES FOR 200 EVOLVED STARS

Using narrow-band spectrophotometric indices interpreted with synthetic spectra computed from model atmospheres, barium abundances have been measured for 200 stars with uncertainties of about 0-3 in [Ba/H]. The results suggest that there is a continuous distribution of [Ba/Fe] from the Ba 11 stars to barium poor stars and that the latter, at least, reflect a variation of [Ba/Fe] in the interstellar medium which may be correlated with [Fe/H]. Several possible new Ba 11 stars have been found and the frequency of Ba 11 stars amongst G and K giants appears to lie between 1 and 4 per cent. Only one of the candidate Ba 11 stars appears to have strong CN and CH absorption and the candidates cover a wide range in luminosity. Masses between 0-5 Mo and 50 Mo were derived for Ba 11 stars which also have spectroscopic gravities or [Pe] derived in other analyses. Most Ba 11 stars appear to have young disk kinematics. It is confirmed that the peculiar colours of many Ba 11 stars are caused by excess blanketing due to CN, CH and C2. © Royal Astronomical Society.