  Electron scattering off the first excited 0+ state in 12C (the Hoyle state)
has been performed at low momentum transfers at the S-DALINAC. The new data
together with a novel model-independent analysis of the world data set covering
a wide momentum transfer range result in a highly improved transition charge
density from which a pair decay width Gamma_pi = (62.3 +- 2.0) micro-eV of the
Hoyle state was extracted reducing the uncertainty of the literature values by
more than a factor of three. A precise knowledge of Gamma_pi is mandatory for
quantitative studies of some key issues in the modeling of supernovae and of
asymptotic giant branch stars, the most likely site of the slow-neutron
nucleosynthesis process.
