Linking 44Ti explosive nucleosynthesis to the dynamics of core-collapse supernovae

We have searched for the three decay lines of the Ti-44 in Cassiopeia A with the spectrometer SPI on-board INTEGRAL The lines at 78.4 and 1157.0 keV have been detected with a flux of (2.1 +/- 0.7) x 10(-5) ph cm(-2) s(-1), consistent with all previous measurements combined. The spectral capabilities of SPI indicate that the Ti-44 ejecta expands at about 430 km s(-1) and moves away from the observer at about 500 km s(-1). Such a small expansion velocity together with the Ti-44 yield of the event are consistent with a spherical explosion but an asymmetric explosion due for instance to prolate neutrino emission could not be definitely excluded. (C) 2008 Elsevier B.V. All rights reserved.