Journal Article

Bars and the symmetry of star formation patterns in the discs of spiral galaxies

M. Rozas, J. H. Knapen and J. E. Beckman

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 301, issue 3, pages 631-639
Published in print December 1998 | ISSN: 0035-8711
Published online December 1998 | e-ISSN: 1365-2966 | DOI:
Bars and the symmetry of star formation patterns in the discs of spiral galaxies

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We present a test for the degree of symmetry in the distribution of the Hα brightness along the arms of a sample of spiral galaxies. The test consists of deriving the cross-correlation function of the Hα brightness as a function of curvilinear distance along pairs of opposed arms, after unfolding the arms geometrically. Our results reveal a significantly greater degree of symmetry in the non-barred population than in the barred. We derive parameters for both bar strength and bar ellipticity, and compare these with the derived cross-correlations to strengthen this conclusion. We suggest that density waves are a probable cause for the appearance of global, i.e. disc-wide, two-fold symmetry in spiral discs. Comparison with published work on abundance gradients in the discs of barred and non-barred galaxies indicates that, as for the abundances, mixing in the spiral disc as a result of the bar potential may well be responsible for our observation that stronger bars are related to reduced two-fold symmetry in the distribution of star-forming regions along the spiral arms.

Keywords: stars: formation; galaxies: spiral; galaxies: structure

Journal Article.  0 words. 

Subjects: Astronomy and Astrophysics

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