Proton-capture rates on carbon isotopes and their impact on the astrophysical 12C/13C ratio

Proton-capture rates on carbon isotopes and their impact on the astrophysical 12C/13C ratio

Skowronski, J.; Boeltzig, A.; Ciani, G. F.; Csedreki, L.; Piatti, D.; Aliotta, M.; Ananna, C.; Barile, F.; Bemmerer, D.; Best, A.; Broggini, C.; Bruno, C. G.; Caciolli, A.; Campostrini, M.; Cavanna, F.; Colombetti, P.; Compagnucci, A.; Corvisiero, P.; Davinson, T.; Depalo, R.; Di Leva, A.; Elekes, Z.; Ferraro, F.; Formicola, A.; Fülöp, Z.; Gervino, G.; Gesue, R. M.; Guglielmetti, A.; Gustavino, C.; Gyürky, G.; Imbriani, G.; Junker, M.; Lugaro, M.; Marigo, P.; Masha, E.; Menegazzo, R.; Paticchio, V.; Perrino, R.; Prati, P.; Rapagnani, D.; Rigato, V.; Schiavulli, L.; Sidhu, R. S.; Straniero, O.; Szücs, T.; Zavatarelli, S.

The 12C/13C ratio is a significant indicator of nucleosynthesis and mixing processes during hy- drogen burning in stars. Its value mainly depends on the relative rates of the 12C(p,γ)13N and 13C(p,γ)14N reactions. Both reactions have been studied at the Laboratory for Underground Nu- clear Astrophysics (LUNA) in Italy down to the lowest energies to date (Ec. m. = 60 keV) reaching for the first time the high energy tail of hydrogen burning in the shell of giant stars. Our cross sections, obtained with both prompt γ-ray detection and activation measurements, are the most precise to date with overall systematic uncertainties of 7–8%. Compared with most of the liter- ature, our results are systematically lower, by 25 % for the 12C(p, γ)13N reaction and by 30 % for 13C(p, γ)14N. We provide the most precise value up to now of 3.6 ± 0.4 in the 20 – 120 MK range for the lowest possible 12C/13C ratio that can be produced during H burning in giant stars.

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