The galactic distribution of open clusters of different ages and the angular velocity of the spiral structure

Results based on the galactic distribution of open clusters of various ages are presented. On the basis of this distribution the shape and angular velocity of the spiral pattern is discussed. The results suggest: (1) scaling down our whole Galaxy, accepting solar radius = 7kpc as the galactocentric distance of the Sun; (2) the angular speed of the pattern lies somewhere between 33 and 36 km/s/kpc (or between 23 and 25 if solar radius = 10 kpc); accordingly the location of the Sun is close to the so called co-rotation circle and, therefore, the galactic position of our solar system is an exclusive one; and (3) the spiral pattern seems to be compatible with long density waves, consequently the source of the wave energy should apparently be looked for in the central regions of the Galaxy.