On real Cartan factors

JBW*-triples can be described (module W*-algebras, compare [13]) by those of type I. Among these the (complex) Cartan factors are the building blocks. We determine for every complex Cartan factor U all conjugations of the underlying complex Banach space and hence all real forms (in the sense of [15]) of U, called real Cartan factors. We also give a concrete list of all isomorphy classes of real Cartan factors which generalizes the classification of LOGS [23] to infinite dimensions. Furthermore, we give an explicit description of the full automorphism group as well as the group of all surjective IR-linear isometries for every non-exceptional real Cartan factor and decide which of the real or complex Cartan factors are isometrically equivalent to each other as real Banach spaces.