Barium Star Orbital Elements Distribution And Abundance Of The Monte-carlo Simulation Calculation

It is very significant for Ba stars to heavy-element nucleosfynthesis and Galactic chemical evolution. The obvious overabundances of heavy-element are observed in Ba stars. However, the luminosity of Ba stars is too low to reach AGB stage, and the nuclear 99Tc have not observed in Ba stars. In general, Ba stars belong to binary system, and their heavy-element overabundances are due to the accreting material from the companions (the former TP-AGB stars and the present white dwarfs).Carrying out a series of Monte-Carlo simulations, the changes of orbital elements of binaries are recalculated for wind accretion scenario of the total angular momentum conservation. As Ba star systems are evolved from G-K star systems, the distribution of orbital eccentricities and periods of Ba stars can show the final orbital character of binaries. Our results show that, during the evolution of a binary system, the system widens as it loses mass, and the orbital period increase, while orbital eccentricity remains nearly constant, which can explain the distribution regulation of orbital elements of normal G-K giant and barium stars and the distribution character of the heavy-element abundances of barium stars.