Network Computation Of Several Elements In Astrophysics

Based on the physical process model of helium burning in stars in astrophysics,a nuclear reaction network from carbon to neon is established under certain physical conditions.The generation path of 19F of fluorine and the sensitivity of some nuclear reactions to 19F in the nuclear reaction network are discussed.This paper analyses the stars of Asymptotic Branch Giant and Wolf-Rayet.The main conclusions are as follows:In the first chapter,we first introduce the evolution stars,then introduce the AGB stars and some nuclear reactions in the process of helium burning of stars,and introduce some previous studies about the origin of 19F.Finally,w this paper gives the innovation and the main conclusions.In Chapter 2,we introduce the establishment of nuclear reaction network and the differential equation model of nuclides changing with time.In this paper,a more perfect nuclear reaction network is established based on the latest nuclear reaction data.Particularly,because 14N(n,Y)15N may also be an effective path for the production of 15N,so the network concludes 14N(n,y)15N.In Chapter 3,the formation of 19F in the helium-hydrogen burning model of AGB star is discussed.According to the established nuclear reaction network and differential equations,a semi-implicit Runge-Kutta algorithm is used to program the numerical calculation.By comparing the curves of various nuclides with the previous studis,it is proved that the nuclear reaction network established in this paper is effective,and the reaction flow rate of some nuclear reactions related to the product of 19F is calculated,and the effective path to the product of 19F is obtained.The sensitivity analysis of 19F for all three types(n,y),(p,y)and(a,y)of nuclear reactions in the nuclear reaction network is calculated,and the important nuclear reactions for the product of 19F are obtained by comparing the results.In chapter 4,we discuss the produact of 19F in helium-burning model of six Wolf-Rayet stars with different mass and temperature.According to the established nuclear reaction network and differential equations,numerical calculations are carried out.The sensitivity analysis of 19F for all the three types(n,y),(p,y)and(a,y)of nuclear reactions in the nuclear reaction network is also calculated.Based on the comparison of the results,the important nuclear reactions for the product of '9F are obtained.It is found that the results are different from those of AGB stars.The chapter 5 makes a summary and analysis of the conclusions of this paper,and gives the prospects for the future.