A quick start guide to BOND: Bayesian Oxygen and Nitrogen abundance   Determinations in H II regions using strong and semistrong lines
  We present a quick-start guide to BOND, a statistical method to derive oxygen and nitrogen abundances in H II regions. BOND compares a set of carefully selected strong and semistrong emission lines to a grid photoionization models. The first novelty, in comparison to other statistical methods, is that BOND relies on the [Ar III]/[Ne III] emission line ratio to break the oxygen abundance bimodality. In doing so, we can measure oxygen and nitrogen abundances without assuming any a priori relation between N/O and O/H. The second novelty is that BOND takes into account changes in the hardness of the ionizing radiation field, which can come about due to the ageing of H II regions or the stochastically sampling of the IMF. We use the emission line ratio He I/Hb, in addition to commonly used strong lines, to constrain the hardness of the ionizing radiation field. Finally, we also stress the pragmatic considerations behind our Bayesian inference. 
N. Vale Asari (1), G. Stasi\'nska (2), C. Morisset (3), R. Cid   Fernandes (1) ((1) UFSC, Brazil, (2) LUTH, Observatoire de ...
astro-ph.GA