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O/H Abundances in the Ringed Galaxy NGC 4736: Mixing Processes in the Interstellar Medium

Published online by Cambridge University Press:  12 April 2016

P. Martin
Affiliation:
Steward Observatory, University of Arizona, Tucson, Az 85721
J. Belley
Affiliation:
CUSLM, Université de Moncton, Edmundston, N.-B., Canada, E3V 2S8

Abstract

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Imaging spectrophotometry in the main nebular lines has been performed on 65 H ɪɪ regions in the ringed galaxy NGC 4736. O/H abundances were derived using the line ratios [O ɪɪɪ]/Hβ and [N ɪɪ]/[O ɪɪɪ] calibrated by Edmunds & Pagel (1984). We show that the O/H scatter in the resonance ring of star forming regions is small, no greater than normally expected in the well-mixed ISM of disks of gas-rich galaxies. The global O/H gradient (−0.046 dex/kpc) in the disk of NGC 4736 is shallower than gradients of normal spirals but comparable to gradients observed in weakly barred spirals. This last result could indicate that radial mixing is or was present in NGC 4736. The oval distortion in the central regions can be responsible for this homogenization but it is also possible that a strong bar was present in the past.

Type
Posters for Part I and Part II
Copyright
Copyright © Astronomical Society of the Pacific 1996

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