Abstract
Asymptotic Giant Branch (AGB) stars are among the most important astrophysical sites influencing the nucleosynthesis and the chemical abundances in the Universe. From a pure nuclear point of view, several processes take part during this peculiar stage of stellar evolution thus requiring detailed experimental cross section measurements. Here, we report on the most recent results achieved via the application of the Trojan Horse Method (THM) and Asymptotic Normalization Coefficient (ANC) indirect techniques, discussing the details of the experimental procedure and the deduced reaction rates. In addition, we report also on the on going studies of interest for AGB nucleosynthesis.
Highlights
Received: 16 December 2021The Asymptotic Giant Branch (AGB) phase is the evolved stage of stars with M ≤ 6 M and is of critical importance for nucleosynthesis
Process (CBP) [15], in lower mass AGB stars, having high precision reaction rates is crucial to make accurate studies of proton capture nucleosynthesis in AGB stars. Isotopes such as 7 Li can undergo proton captures at few million Kelvin and the nucleosynthesis of other species, such as 17 O and 26 Al is sensitive to environmental temperature; their abundances can probe stellar interiors and/or, according to nuclear physics inputs employed in stellar models, might hit different scenarios for their production
Nuclear reaction cross section measurements of interest for nuclear astrophysics are difficult to be performed in terrestrial laboratories mainly because of Coulomb barrier penetration and electron screening effects [25]
Summary
The Asymptotic Giant Branch (AGB) phase is the evolved stage of stars with M ≤ 6 M and is of critical importance for nucleosynthesis. During the TDU, proton-rich materials penetrate the bottom edge of the convective zone down to the stellar layers rich in C and 4 He, which are below the H-shell When this latter returns to burn the injected protons, it allows for the formation of the so-called C-pocket through the C(p,γ) N(β+ ν) C reaction chain, and thanks to the abundance of α particles, the C(α,n) O delivers a flux of neutrons allowing the s-process to take place. Process (CBP) [15], in lower mass AGB stars, having high precision reaction rates is crucial to make accurate studies of proton capture nucleosynthesis in AGB stars Isotopes such as 7 Li can undergo proton captures at few million Kelvin and the nucleosynthesis of other species, such as 17 O and 26 Al is sensitive to environmental temperature; their abundances can probe stellar interiors and/or, according to nuclear physics inputs employed in stellar models, might hit different scenarios for their production. The Asymptotic Normalization Coefficient (ANC) method [22,23,24]
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