| Abstract: | An investigation of suspected OB stars on plates of the Schmidt telescope of Karl Schwarzschild Observatory Tautenburg gave the following results: I. There exists a sharp boundary of the M 31 disk. For distances larger than R = 30 kpc from the centre no OB stars of the Andromeda galaxy could be found. 2. The isolated OB stars in the outer regions of M 31 fit into the spiral structure. 3. The suspected OB stars outside M 31 (R>30 kpc) in all probability belong to our own galaxy. It is to be expected that they partly are blue horizontal branch stars of extreme population II, partly white dwarfs rather far left of the black body line in the two colour diagram. |
