N/O in Spiral Disks: An Algorithm for Abundance Determinations

Session 108 - HII Regions.
Display session, Thursday, January 18
North Banquet Hall, Convention Center

[108.01] N/O in Spiral Disks: An Algorithm for Abundance Determinations

T. Thurston, R. B. C. Henry (U. Oklahoma), M. G. Edmunds (U. Wales, College of Cardiff)

We obtain nitrogen abundances in the \ionH2 regions of selected spiral galaxies by using a new algorithm developed from grids of photoionization models. The new method requires only the observation of optical [\ionN2], [\ionO2], and [\ionO3] lines. We show the self-consistency of the new method, and also the agreement with more detailed modeling of individual \ionH2 regions. Gradients in [N/O] against effective radius are presented for a well-observed subset of galaxies from a Vila-Costas and Edmunds sample (\citeve93).

Program listing for Thursday