Radioactive Al and Fe in the Milky Way: Implications of the RHESSI detection of Fe
Institut d'Astrophysique de Paris, 98bis Bd. Arago, 75104 Paris, France
Corresponding author: firstname.lastname@example.org
Accepted: 14 March 2004
The recent detection of gamma-ray lines from radioactive 26Al and 60Fe 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 [CITE]); in the light of those results, this observation would suggest then that SNII are the major sources of 26Al in the Milky Way, since no other conceivable source produces substantial amounts of 60Fe. However, more recent theoretical studies find that SNII produce much higher 60Fe/26Al ratios than previously thought and, therefore, they cannot be the major 26Al sources in the Galaxy (otherwise 60Fe would be detected long ago, with a line flux similar to the one of 26Al). Wolf-Rayet stars, ejecting 26Al (but not 60Fe) 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 and metallicities up to 3 ), are required to settle the issue.
Key words: Galaxy: abundances / nuclear reactions, nucleosynthesis, abundances
© ESO, 2004