Chinese Acad Sci, Inst High Energy Phys, Beijing 100039, Peoples R China
; Guangxi Normal Univ, Dept Phys & Eletron Sci, Guilin 541004, Peoples R China
; Hebei Normal Univ, Dept Phys, Shijiazhuang 050016, Peoples R China
; Natl Lab Heavy Ion Accelerator Lanzhou, Ctr Theoret Nucl Phys, Lanzhou 730000, Peoples R China
We apply the parametric model to fit the surface abundances of three lead-rich stars (HD187861, HD196944 and HD224959) without adopting any specific stellar model. It shows that the calculated result can fit the observed data well whether the reaction branchings are taken into account or not. Besides, by the comparison of the model parameters of the three lead-rich stars with, those of two very metal-poor stars (LP625-44 and LP706-7), we find out that the average neutron exposure of the former is larger than that of the latter, but the dredge-up extent is smaller. We come to the conclusion that the parametric model is significant of constraints on the stellar model, though it is very simple.