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HK: Fachverband Hadronen und Kerne

HK 50: Nuclear Astrophysics

HK 50.1: Group Report

Wednesday, March 18, 2009, 14:00–14:30, H-ZO 60

The ¹²C+¹²C fusion reactions at astrophysical energies — •Frank Strieder¹, Hans-Werner Becker¹, Nicola DeCesare², Antonino Di Leva^1,2, Antonio D’Onofrio², Lucio Gialanella², Benedetta Limata², Claus Rolfs¹, Jeff Schweitzer³, Tim Spillane³, Oscar Straniero⁴, Filippo Terrasi², and Jim Zickefoose³ — ¹Ruhr-Universität Bochum, Germany — ²INFN Napoli, Italy — ³University of Connecticut, USA — ⁴Osservatorio Astronomico di Teramo, Italy

The fusion reactions ¹²C(¹²C,α)²⁰Ne and ¹²C(¹²C,p)²³Na are referred to as carbon burning in stars. In massive stars the ashes produced during helium burning become the fuel for further nuclear-burning processes, leading to the synthesis of most elements with mass numbers larger than 20. Consequently, these fusion reactions represent key processes since they influence not only the nucleosynthesis but also the subsequent evolution of a star. However, at the astrophysical relevant energies the reaction rate of these fusion reactions is not very well known and provided only by extrapolations of high energy data. The reactions have now been studied from E = 1.5 to 4.75 MeV by γ-ray and particle spectroscopy using thick carbon targets. The data reveal new resonances, in particular strong resonances at E<2.3 MeV, which lie in the range of the Gamow peak for carbon burning in massive stars, which takes place at temperatures T ≈ (5−10)×10⁸ K. These resonances increase the present reaction rate significantly in this temperature range. The impact of the results on various astrophysical sites, e.g. supernovae progenitor stars, will be discussed.