Abundances in Spiral Galaxies: Evidence for Primary Nitrogen Production
Abstract
We present the results of nitrogen and oxygen abundance measurements for 185 HII regions spanning a range of radius in 13 spiral galaxies. As expected, the nitrogen-to-oxygen ratio increases linearly with the oxygen abundance for high metallicity HII regions, indicating that nitrogen is predominately a secondary element. However, the nitrogen-to-oxygen ratio plateaus for oxygen abundances less than 1/3 solar (12+log(O/H) < 8.45), as is also seen in low metallicity dwarf galaxies. This result suggests that the observed trend in dwarf galaxies is not due to outflow of enriched material in a shallow gravitational potential. While the effects of infall of pristine material and delayed nitrogen delivery are still unconstrained, nitrogen does appear to have both a primary and secondary component at low metallicities in all types of galaxies.
Cite
@article{arxiv.astro-ph/9802147,
title = {Abundances in Spiral Galaxies: Evidence for Primary Nitrogen Production},
author = {L. van Zee and J. J. Salzer and M. P. Haynes},
journal= {arXiv preprint arXiv:astro-ph/9802147},
year = {2009}
}
Comments
10 pages, 2 figures, uses AASTex and psfig. Accepted to ApJL