128Xe and 130Xe: Testing He-shell burning in AGB stars

Abstract

The s-process branching at 128I has been investigated on the basis of new, precise experimental (n,g) cross sections for the s-only isotopes 128Xe and 130Xe. This branching is unique, since it is essentially determined by the temperature- and density-sensitive stellar decay rates of 128I and only marginally affected by the specific stellar neutron flux. For this reason it represents an important test for He-shell burning in AGB stars. The description of the branching by means of the complex stellar scenario reveals a significant sensitivity to the time scales for convection during He shell flashes, thus providing constraints for this phenomenon. The s-process ratio 128Xe/130Xe deduced from stellar models allows for a (9+-3)% p-process contribution to solar 128Xe, in agreement with the Xe-S component found in meteoritic presolar SiC grains.

24 pages, 9 figures, accepted for publication in Astophysical Journal

References in corpus (4)

• Nucleosynthesis in Massive Stars With Improved Nuclear and Stellar Physics
• Neutron capture in low mass Asymptotic Giant Branch stars: cross sections and abundance signatures
• The endpoint of the rp process on accreting neutron stars
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• Hydrodynamic simulations of He-shell flash convection
• The s Process and Beyond
• Survival of Nature's Rarest Isotope 180Ta under Stellar Conditions
• The Status and Future of Direct Nuclear Reaction Measurements for Stellar Burning
• Radioactivities in Low- and Intermediate-Mass Stars
• Time scales of the s process - from minutes to ages
• Measurements of neutron-induced reactions in inverse kinematics and applications to nuclear astrophysics
• Experiments towards a neutron target for measurements in inverse kinematics
• The Hydrodynamic Environment for the s Process in the He-Shell Flash of AGB Stars