Journal Article

A two-component outer ring and Galactic spiral structure

A. M. Mel’nik and P. Rautiainen

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 418, issue 4, pages 2508-2518
Published in print December 2011 | ISSN: 0035-8711
Published online December 2011 | e-ISSN: 1365-2966 | DOI:
A two-component outer ring and Galactic spiral structure

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A model of the Galaxy with a ring R1R2 can explain some large-scale morphological features of Galactic spiral structure. The Carina–Sagittarius arm could consist of two ascending segments of outer rings R1 and R2, which almost touch each other near the Carina region. The Perseus and Crux arms can be partially identified with the descending segments of ring R2. A model of a two-component outer ring can also explain the existence of some maxima in diagrams of (l, VLSR), which are supposed to correspond to directions tangential to the spiral arms. On the basis of numerical simulations, we propose two sketches of the ring structure of the Galaxy that include a bar, two outer rings, an inner ring and nuclear gas condensation, which may be a nuclear ring. Both sketches can explain the position of the Carina–Sagittarius arm with respect to the Sun.

Keywords: Galaxy: kinematics and dynamics; Galaxy: structure

Journal Article.  7975 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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