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Spallation nucleosynthesis by accelerated charged-particles in stellar envelopes of magnetic stars

par Goriely, Stéphane
Editeur scientifique Arnould, Marcel ;Lewitowicz, M.;Emling, H.;Akimune, Hidetoshi;Ohta, Masahisa;Utsunomiya, Hiroaki;Wada, T.;Yamagata, Tamio
Référence AIP Conference proceedings(891), Proceedings of Tours Symposium on Nuclear Physics VI, page (246-253)
Publication Publié, 2007

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Résumé :

Recent observations have suggested the presence of radioactive elements, such as Tc, Pm and 84 ≤ Z ≤ 99 elements at the surface of the chemically-peculiar magnetic star HD 101065, also known as Przybylski's star. The peculiar 35 < Z < 82 abundance pattern of HD 101065 has been so far explained by diffusion processes in the stellar envelope. However, such processes cannot be called for to explain the origin of short-lived radio-elements. The large magnetic field observed in Ap stars can be at the origin of a significant acceleration of charged-particles, mainly protons and α-particles, that in turn can by interaction with the stellar material modify the surface content. The present contribution explores to what extent the irradiation process corresponding to the interaction of the stellar material with energetic particles can by itself only explain the abundances determined by observation at the surface of the chemically peculiar star HD 101065, as well as other chemically peculiar star. Due to the unknown characteristics of the accelerated particles, a purely parametric approach is followed, taken as free parameters the proton and α-particle flux amplitude and energy distribution as well as the time of irradiation. The specific simulations considered here can explain many different observational aspects. In particular, it is shown that a significant production of Z > 30 heavy elements can be achieved. The most attractive feature of the irradiation process is the significant production of Tc and Pm, as well as actinides and sub-actinides.