Kinematics of the outer pseudorings and the spiral structure of the Galaxy

Abstract

The kinematics of the outer rings and pseudorings is determined by two processes: the resonance tuning and the gas outflow. The resonance kinematics is clearly observed in the pure rings, while the kinematics of the gas outflow is manifested itself in the pseudorings. The direction of systematical motions in the pure rings depends on the position angle of a point with respect to the bar major axis and on the class of the outer ring. The direction of the radial and azimuthal components of the residual velocities of young stars in the Perseus, Carina, and Sagittarius regions can be explained by the presence of the outer pseudoring of class R1R2' in the Galaxy. We present models, which reproduce the directions and values of the residual velocities of OB-associations in the Perseus and Sagittarius regions, and also model reproducing the directions of the residual velocities in the Perseus, Sagittarius, and Carina regions. The kinematics of the Sagittarius region accurately defines the solar position angle with respect to the bar elongation, theta_b=45 (+/-5) deg.

16 pages, 10 figures, accepted for publication in Astronomy Letters

References in corpus (3)

• The formation of spiral arms and rings in barred galaxies
• Tracing the long bar with red-clump giants
• Milky Way Gas Dynamics

Cited by in corpus (7)

• The morphology of the Milky Way - I. Reconstructing CO maps from simulations in fixed potentials
• Kinematics of OB-associations in Gaia epoch
• Classical Cepheids in the Galactic outer ring R1R2'
• Probabilities for Solar Siblings
• Galactic resonance rings. Modelling of motions in the wide solar neighborhood
• Distance scale for high-luminosity stars in OB associations and in field with Gaia DR2. Spurious systematic motions
• Influence of the Galactic bar on the kinematics of the disc stars with Gaia EDR3 data