Abundance analysis of the recurrent nova RS Ophiuchi (2006 outburst)

TL;DR

This study analyzes the elemental abundances in the ejecta of the 2006 outburst of recurrent nova RS Ophiuchi using spectral modeling, revealing significant element enhancements and estimating the ejected mass.

Contribution

It provides a detailed abundance analysis of RS Oph's ejecta during its 2006 outburst using photoionization modeling, which is a novel application for this event.

Findings

Ejecta are enriched in helium, nitrogen, neon, iron, and argon.

Estimated ejected mass is 3.4-4.9 x 10^{-6} solar masses.

Model spectra fit well with observed spectra at two epochs.

Abstract

We present an analysis of elemental abundances of ejecta of the recurrent nova RS Oph using published optical and near-infrared spectra during the 2006 outburst. We use the CLOUDY photoionization code to generate synthetic spectra by varying several parameters, the model generated spectra are then matched with the observed emission line spectra obtained at two epochs. We obtain the best fit model parameters through the $\chi^{2}$ minimization technique. Our model results fit well with observed optical and near-infrared spectra. The best-fit model parameters are compatible with a hot white dwarf source with T$_{BB}$ of 5.5 - 5.8 $\times$ 10$^{5}$ K and roughly constant a luminosity of 6 - 8 $\times$ 10$^{36}$ ergs s$^{-1}$. From the analysis we find the following abundances (by number) of elements with respect to solar: He/H = 1.8 $\pm$ 0.1, N/H = 12.0 $\pm$ 1.0, O/H = 1.0 $\pm$ 0.4, Ne/H = 1.5 $\pm$ 0.1, Si/H = 0.4 $\pm$ 0.1, Fe/H = 3.2 $\pm$ 0.2, Ar/H = 5.1 $\pm$ 0.1, and Al/H = 1.0 $\pm$ 0.1, all other elements were set at the solar abundance. This shows the ejecta are significantly enhanced, relative to solar, in helium, nitrogen, neon, iron and argon. Using the obtained parameter values, we estimate an ejected mass in the range of 3.4 - 4.9 $\times$ 10$^{-6}$ M$_{\odot}$ which is consistent with observational results.