  English abstract: This work contains of five chapters: The first one deals
with Morita equivalence of star algebras. In particular star algebras which are
equipped with a symmetry given by a Hopf (star-) algebra. In the second chapter
we describe the equivariant Picard group and the equivariant Picard groupoid,
which are a direct consequence of the results from the first chapter. We
calculated the kernel and the image of the groupoid morphism from the
equivariant Picard groupoid into the normal one. We give furthermore a
formalized version of Morita invariance: given by a functor from the Picard
groupoid to another category. This is shown for several examples. In the third
chapter we show the connection between Hopf equivariant Morita equivalence of
star algebras and the Morita equivalence of cross-product algebras. The forth
chapter deals with deformation quantization and gives an extended introduction
to (invariant) star products. In the fifth chapter we show the Hopf
equivariance of deformed algebras (i.e. of hermitian star products). This is a
important examples which concludes the previous chapters.
