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arXiv · 1505.00337

On the radial abundance gradients in disks of irregular galaxies

L. S. Pilyugin·E. K. Grebel·I. A. Zinchenko
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Abstract

We determine the radial abundance distributions across the disks of fourteen irregular galaxies of the types Sm and Im (morphological T types T = 9 and T =10) as traced by their HII regions. The oxygen and nitrogen abundances in HII regions are estimated through the Te method or/and with the counterpart method (C method). Moreover, we examine the correspondence between the radial abundance gradient and the surface brightness profile. We find that irregular galaxies with a flat inner profile (flat or outwardly increasing surface brightness in the central region) show shallow (if any) radial abundance gradients. On the other hand, irregular galaxies with a steep inner profile (with or without a bulge or central star cluster) usually show rather steep radial abundance gradients. This is in contrast to the widely held belief that irregular galaxies do not usually show a radial abundance gradient.

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L. S. Pilyugin, E. K. Grebel, I. A. Zinchenko. 2015-05-02. On the radial abundance gradients in disks of irregular galaxies. https://arxiv.org/abs/1505.00337

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