Comparative roles of pp chain reactions as a trigger for suprathermal processes in the solar core

Continuing the study of suprathermal effects in the solar core [Phys. Rev. C 91, 028801 (2015)PRVCAN0556-281310.1103/PhysRevC.91.028801; J. Phys. G 44, 045202 (2017)JPGPED0954-389910.1088/1361-6471/aa5f30], we examine the roles of different pp chain processes generating fast α particles as trigger for suprathermal B(α,p)A reactions neglected in standard solar model simulations. The suprathermal impact on the balance of the p+17Oα+14N reactions involved in the solar CNO cycle is determined. It is obtained that MeV α particles born in the Li7(p,α)α and He3(3He,2p)α reactions are the main agents that are able to crucially change the reaction balance through an appreciable enhancement of the reverse (α,p) reaction. The comparative role of the p+7Li and He3+3Heα particles is clarified. It is found that the former particles control the reverse N14(α,p)17O reaction in the inner core, while the latter ones play a dominant role in the outer core, additionally increasing the (α,p) reaction rate by several times and providing favorable conditions for synthesis of some elements. In particular, we show that the total suprathermal enhancement of O17 and O18 mass fractions in the outer core can reach ∼80 or 50, depending on a model for α-particle energy loss used in the simulation. In this context, we note that the p+7Liα particles alone provide the mass fraction enhancement by a factor of 20 or less.