Periodic pattern in the residual velocity field of OB-Associations

Abstract

Abstract An analysis of the space velocity field of the OB-associations within 3 kpc of the Sun revealed a periodic pattern in the residual radial velocity field along the galactic radius-vector with a typical scale length of λ = 2.0 ± 0.2 and a mean amplitude of f R = 7 ± 1 km s−1. The fact that the radial residual velocities of almost all OB-associations in rich star-gas complexes are directed toward the Galactic center proves that the region considered is inside the corotation circle. The azimuthal velocity field of OB-associations exhibits a well-defined periodicity in the region l 180°. The galactocentric distances of the Cygnus and Perseus arms as inferred from separate analyses of radial and azimuthal residual velocity fields agree with each other within the errors.