Nucleosynthesis Parameters Of The Lead Star And The Radiation Of Non-lead Stars Of The Study

In this paper we use the parametric model, combining AGB nuclear synthesis radiation model, to explore the physical mechenism of formation of both Pb stars and no-Pb stars with the elemental abundances observed on their surface . We suggest a new concept of component coefficients to describe the contributions of individual neutron-capture progress to both Pb stars and no-Pb stars. The overlap factor in the Pb stars were produced lies between 0.8 and 0.88; and the overlap factor in no-Pb stars are smaller, lying between 0.1 and 0.66. Taking into account the overlap factor-core mass law and the initial-final mass relations, this wide range of values of overlap factors could possibly be explained by the wide range of initial-mass values of AGB stars at low metallicity. With the ascent of initial-mass of AGB stars, the core-mass values also is on the increase, while the overlap factors are on the decrease. So no-Pb-stars had been possible created from the pollution of the AGB stars with larger initial-mass, and the Pb-starts had been created from AGB stars with smaller initial-mass. The neutron exposure per circle deduced for both Pb-stars and no-Pb-stars are almost equivalent and lies between 0.44 and 0.88. The most uncertainty in the radiation model of nuclear synthesis is the formation of q. The nuclear synthesis region q is more than 10 times of that of normal AGB model, and this suggest that the q change to larger than that of normal AGB model. Then, this factor will result in directly the descent of the density of ¹³C in the nuclear synthesis region. So, the neutron exposure will also decrease to the same extent. And the result is consistent with our outcome of Pb stars analysis. It is clear that our results are different from that of normal AGB model and offer crucial bondage for the normal AGB model. Because of the larger initial-mass stars with shorter neutron exposure time, the neutron exposure of per pulse become smaller. This will be the possible reason for smaller neutron exposure of no-Pb stars with smaller q.