Title: Identification and study of nucleosynthesis sources in the Carina region
Proposal ID: 0120154
Subject category: Nucleosynthesis
Principal investigator: knoedlseder
Institute: Centre d'Etude Spatiale des Rayonnements
Abstract
We propose to map the gamma-ray emission lines due to radioactive decay of 26Al (1.809 MeV) and 60Fe (1.173
and 1.332 MeV) and the positron annihilationline at 511 keV in the Carina region with unprecedented spatial
and spectral resolution. In the COMPTEL all-sky 1.809 MeV map, Carina stands out as the most concentrated
localised emission feature among the brightest regions. This region harbours the highest concentration of
young open clusters along the galactic plane and its associated nebulosity -- the Carina nebula -- is one of
the most prominent HII regions of the Galaxy. A detailed census of all known associations and stellar
clusters shows that their expected total 1.809 MeV emission falls short by a factor 5-25 to explain the
integrated COMPTEL flux from this region. This discrepancy, which is not found for other regions in the
Galaxy (Cygnus), most likely indicates that additional unknown nearby sources contribute significantly to
the 26Al production. To resolve this puzzle represents one of the main aims of our proposal. The proposed
1.809 MeV mapping with a high spatial resolution will allow to pin down the location of the 26Al emission
and to identify possible new sources. The study of the 1.809 MeV line will also allow us to constrain its
nucleosynthetic origin and to quantify the relative contribution from hydrostatic burning phases of massive
stars and core-collapse (supernova) events. Simultaneously the observations of the 60Fe gamma-ray lines
at 1.173 and 1.332 MeV, originating only from supernovae, will set strong constraints on predictions of
core-collapse nucleosynthesis. We will also study the positron 511 keV line and annihilation continuum,
which carries valuable information about positron escape in such explosive events, providing important
insights in the origin of galactic positrons in general.