The puzzle of the synthesis of the rare nuclide La
Institut d'Astronomie et d'Astrophysique, Université Libre de Bruxelles, CP 226, 1050 Brussels, Belgium
Corresponding author: S. Goriely, firstname.lastname@example.org
Accepted: 3 July 2001
The calculations of the p-process in the O/Ne layers of Type II supernovae are quite successful in reproducing the solar system content of p-nuclides. They predict, however, a significant underproduction of the rare odd-odd nuclide 138La. A model for the explosion of a 25 star with solar metallicity is used to suggest that -captures on 138Ba may well be its most efficient production mechanism. The responsibility of an inadequate prediction of the 138La and 139La photodisintegration rates in the too low production of 138La is also examined quantitatively. A detailed discussion of the theoretical uncertainties in these rates suggest that the required rate changes are probably too high to be fully plausible. Their measurement would be most welcome. They would help disentangling the relative contributions of thermonuclear and neutrino processes to the 138La production.
Key words: nuclear reactions, nucleosynthesis, abundances / solar system: general
© ESO, 2001