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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Combined dynamical effects of the bar and spiral arms in a Galaxy model. Application to the solar neighbourhood

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Michtchenko, T. A. [1] ; Lepine, J. R. D. [1] ; Barros, D. A. [1] ; Vieira, R. S. S. [1]
Total Authors: 4
[1] Univ Sao Paulo, IAG, Rua Matao 1226, Cidade Univ, BR-05508090 Sao Paulo - Brazil
Total Affiliations: 1
Document type: Journal article
Source: Astronomy & Astrophysics; v. 615, JUL 6 2018.
Web of Science Citations: 3

Context. Observational data indicate that the Milky Way is a barred spiral galaxy. Computation facilities and availability of data from Galactic surveys stimulate the appearance of models of the Galactic structure, however further efforts are needed to build dynamical models containing both spiral arms and the central bar/bulge. Aims. We expand the study of the stellar dynamics in the Galaxy by adding the bar/bulge component to a model with spiral arms introduced in one of our previous publications. The model is tested by applying it to the solar neighbourhood, where observational data are more precise. Methods. We model analytically the potential of the Galaxy to derive the force field in its equatorial plane. The model comprises an axisymmetric disc derived from the observed rotation curve, four spiral arms with Gaussian-shaped groove profiles, and a classical elongated/oblate ellipsoidal bar/bulge structure. The parameters describing the bar/bulge are constrained by observations and the stellar dynamics, and their possible limits are determined. Results. A basic model results in a bar of 2.9 kpc in length, with a mass of the order of a few 10(9) M-circle dot (which does not include the axisymmetric part of the bulge, which has a mass of about 1010 M-circle dot). The size and orientation of the bar are also restricted by the position of masers with Very Long Baseline Interferometry (VLBI). The bar's rotation speed is constrained to Omega(bar) < 50 km s(-1) kpc(-1) taking into account the allowed mass range. Conclusions. We conclude that our basic model is compatible with observations and with the dynamical constraints. The model explains simultaneously the bulk of the main moving groups, associated here with the spiral corotation resonance, and the Hercules stream, associated with several inner high-order spiral resonances; in particular, with the 8/1 resonance. From the dynamical constraints on the bar's angular speed, it is unlikely that the bar's outer Lindblad resonance (OLR) lies near the solar circle; moreover, its proximity would compromise the stability of the local arm structure. (AU)

FAPESP's process: 09/54006-4 - A computer cluster for the Astronomy Department of the University of São Paulo Institute of Astronomy, Geophysics and Atmospheric Sciences and for the Cruzeiro do Sul University Astrophysics Center
Grantee:Elisabete Maria de Gouveia Dal Pino
Support type: Multi-user Equipment Program
FAPESP's process: 15/10577-9 - Chaos and integrability in galactic disks
Grantee:Ronaldo Savioli Sumé Vieira
Support type: Scholarships in Brazil - Post-Doctorate