Oriented Event Shapes in Hadronic Z Decays

Using about 4 million events recorded with the ALEPH detector at LEP I, distributions of various event-shape variables are measured as a function of the polar angle of the thrust axis with respect to the e+e- beam direction cos(theta). New calculations which include the event orientation are fitted to the data yielding a measurement of the strong coupling constant alpha_s. The result is compared to that obtained from unoriented event-shape distributions. Preliminary results on alpha_s and on the size of the QCD-corrections to the angular distribution are given.