Barium Abundances of <scp>A–F–G Type</scp> Stars in the Hyades Cluster

ABSTRACT With an aim of clarifying the extent and parameter‐dependence of compositional anomaly of barium in A‐type stars, Ba abundances were spectroscopically determined based on Ba ii 6141/6496 lines for 89 (23 A‐type and 66 F–G‐type) main‐sequence stars belonging to the members of Hyades cluster by taking into account the non‐LTE effect and the hyper‐fine‐structure effect. While the non‐LTE effect tends to strengthen lines in G stars, it acts in the direction of line weakening in the regime of A stars due to increasing importance of overionization. The Ba abundances of G stars turned out almost constant (), indicating that the primordial composition of Ba in Hyades is mildly supersolar by dex. In contrast, A‐type stars show Ba overabundances of considerably large dispersion (0 [Ba/H] ). Since this Ba excess tends to increase with an increase/decrease in /, these two parameters may be essential for producing or controlling the anomaly. Regarding Hyades F‐type stars, their Ba abundances are not uniform but show a broad depression (by dex) around K, interestingly coinciding with the location of Li‐dip.