  Cosmic nucleosynthesis co-produces unstable isotopes, which emit
characteristic gamma-ray emission lines upon their radioactive decay that can
be measured with SPI on INTEGRAL. High spectral resolution allows to derive
velocity constraints on nucleosynthesis ejecta down to ~100 km/s. Core-collapse
supernovae apparently do not always produce significant amounts of 44Ti, as in
the Galaxy fewer sources than expected from the supernova rate have been found.
INTEGRAL's 44Ti data on the well-observed Cas A and SN1987A events are evidence
that non-spherical explosions and 44Ti production may be correlated.
Characteristic gamma-ray lines from radioactive decays of long-lived 26Al and
60Fe isotopes have been exploited to obtain information on the structure and
dynamics of massive stars in their late evolution and supernovae, as their
yields are sensitive to those details. The extended INTEGRAL mission
establishes a database of sufficiently-deep observations of several specific
regions of massive star groups, such as Cygnus, Carina, and Sco-Cen. In the
inner Galaxy, 26Al nucleosynthesis gamma-rays help to unravel the Galaxy's
structure and the role of a central bar, as the kinematically-shifted 26Al
gamma-ray line energy records the longitude-velocity behavior of hot
interstellar gas. Thus, INTEGRAL has consolidated the feasibility of
constraining cosmic nucleosynthesis through gamma-ray line observations. Due to
its extended mission INTEGRAL maintains its chance to also see rare
sufficiently-nearby events, such as a nova to provide first nova
nucleosynthesis measurements of 7Be and 22Na production.
