Radioactive $\mathsf{^{26}}$Al and $\mathsf{^{60}}$Fe in the Milky Way: Implications of the RHESSI detection of $\mathsf{^{60}}$Fe

The recent detection of gamma-ray lines from radioactive 26 Al and 60 Fe in the Milky Way by the RHESSI satellite calls for a reassessment of the production sites of those nuclides. The observed gamma-ray line flux ratio is in agreement with calculations of nucleosynthesis in massive stars, exploding as SNII (Woosley & Weaver 1995); in the light of those results, this observation would suggest then that SNII are the major sources of 26 Al in the Milky Way, since no other conceivable source produces substantial amounts of 60 Fe. However, more recent theoretical studies find that SNII produce much higher 60 Fe/ 26 Al ratios than previously thought and, therefore, they cannot be the major 26 Al sources in the Galaxy (otherwise 60 Fe would be detected long ago, with a line flux similar to the one of 26 Al). Wolf-Rayet stars, ejecting 26 Al (but not 60 Fe) in their stellar winds, appear then as a most natural candidate. We point out, however, that this scenario faces also an important difficulty. Forthcoming results of ESA's INTEGRAL satellite, as well as consistent calculations of nucleosynthesis in massive stars (including stars of initial masses as high as 100 Mand metallicities up to 3 Z� ), are required to settle the issue.