Speaker
Diego Vescovi
(GSSI & INFN Perugia)
Description
Recent improvements in stellar models for intermediate-mass and massive stars are recalled, together with their expectations for the production of radioactive nuclei with lifetime tau 25 Myr, in order to re-examine the origins of now extinct radioactivities, found to be alive in the Early Solar System. While the inheritance from Galactic evolution broadly explains the concentrations of most of them +06, 26Al, 56Fe, 41Ca and 135Cs require one or more nucleosynthesis events occured close in time and space to the solar formation.
We outline the difficulties to account for the required nuclei by Asymptotic Giant Branch stars. Recent physical models predict the ubiquitous formation of a 13C reservoir as a source for efficient neutron captures.
As a consequence, even in presence of 26Al production from Deep Mixing or Hot Bottom Burning, the foreseen ratio 26Al 107Pd remains incompatible with the measured data, due to a large excess in 107Pd. This is shown with reference to two different approaches to Deep Mixing.
Instead, recent revisions invoking specific supernovae of relatively low mass and/or scenarios for the sequential contamination of the pre-solar molecular cloud would most probably induce a huge excess on 60Fe and unacceptaly high excesses on stable isotopes. The limited parameter space remaining to be explored for solving this puzzle is discussed.
Primary authors
Diego Vescovi
(GSSI & INFN Perugia)
Maurizio Busso
(INFN Perugia)
