Kinematics of the outer pseudorings and the spiral structure of the Galaxy |
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Authors: | A M Mel’nik P Rautiainen |
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Institution: | 1.Sternberg Astronomical Institute,Moscow,Russia;2.Astronomy Division, Department of Physical Sciences,University of Oulu,Oulun yliopisto,Finland |
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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 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 R
1
R′2 in the Galaxy. We present models which reproduce the values and directions 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, θ
b = 45° ± 5°. |
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Keywords: | |
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