  Chemical compositions of four barium stars HD 26886, HD 27271, HD 50082 and
HD 98839 are studied based on high resolution, high signal-to-noise Echelle
spectra. Results show that all of them are disk stars. Their \alpha and iron
peak elements are similar to the solar abundances. The neutron-capture process
elements are overabundant relative to the Solar. The heavy-element abundances
of the strong Ba star HD 50082 are higher than those of other three mild Ba
stars. Its mass is 1.32Msun (+0.28,-0.22Msun), and is consistent with the
average mass of strong Ba stars (1.5Msun). For mild Ba star HD 27271 and HD
26886, the derived masses are 1.90Msun (+0.25,-0.20Msun) and 2.78Msun
(+0.75,-0.78M_sun), respectively, which are consistent with the average mass of
mild Ba stars. We also calculate the theoretical abundances of Ba stars by
combining the AGB stars nucleosynthesis and wind accretion formation scenario
of Ba binary systems. The comparisons between the observed abundance patterns
of the sample stars with the theoretical results show that wind accretion
scenario can explain the abundance patterns of HD 50082 and HD 27271 well, but
fail to explain the abundances of HD 26886. It means that the mild Ba star HD
26886, with shorter orbital period (P<1600 d), may be formed from other
scenarios. The high mass mild Ba star HD 98839, with 3.62M_sun, and with very
long orbital period (P>11000 d), may be either a star with the heavy elements
enriched by itself or a "true Ba" star.
