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.
@article{arxiv.astro-ph/0405065,
title = {128Xe and 130Xe: Testing He-shell burning in AGB stars},
author = {R. Reifarth and F. Kaeppeler and F. Voss and K. Wisshak and R. Gallino and M. Pignatari and O. Straniero},
journal= {arXiv preprint arXiv:astro-ph/0405065},
year = {2009}
}
Comments
24 pages, 9 figures, accepted for publication in Astophysical Journal