paper

Abundances in Spiral Galaxies: Evidence for Primary Nitrogen Production

arXiv:astro-ph/9802147 · doi:10.1086/311263

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.

10 pages, 2 figures, uses AASTex and psfig. Accepted to ApJL

References in corpus (2)

Cited by in corpus (107)