The abundance pattern of two barium stars in the Galactic halo: HD 104340 and HD 206983

We present the abundance pattern of two barium stars in the Galactic halo, HD 104340 and HD 206983, based on high-resolution optical spectra. We also determined the spectroscopic stellar atmospheric parameters, temperature, a nd microturbulent velocity, as well as stellar surface gravity from a solut ion of excitation and ionization equilibria of Fe I and Fe II lines under t he assumption of local thermodynamic equilibrium. The abundance analysis re veals HD 104340 to be a metal-poor K giant with [Fe/H] = -1.72 and HD 20698 3 also a metal-poor K giant with [Fe/H] = -1.43. From a set of Fe I lines, the radial velocity is found to be 263.3 +/- 0.6 km s(-1) and -319.2 +/- 4. 4 km s(-1) for HD 104340 and HD 206983, respectively. Their high velocity, low metallicity, and high galactic latitude imply that both stars are membe rs of a Galactic halo population. From our study and by using information f rom the literature we believe that HD 206983 is another member of a group k nown as metal-deficient barium stars. We compare the abundance pattern with the abundances of a halo population. We found that the abundances of the i ron group, a-elements, manganese, copper, and zinc, as well as sodium and m agnesium, of HD 104340 and HD 206983 follow the abundance pattern of a halo population. The heavy element abundance pattern of both stars shows enhanc ement by a factor of 4-8 with respect to the metal-poor stars with the same metallicity as that analyzed by us. We also discuss the abundances of the s-process elements and compare our results with other objects that display the same degree of enrichment due to neutron capture reactions, binary syst ems, and AGB stars, through a diagram of metallicity versus neutron exposur e given by the [hs/ls] index.