Spitzer and ground-based infrared observations of the 2006 eruption of RS Ophiuchi

TL;DR

This paper reports infrared observations of the 2006 RS Ophiuchi eruption, revealing complex emission lines, multiple temperature regions, and elemental abundance estimates in the nova's ejecta and surrounding environment.

Contribution

It provides detailed infrared spectral analysis of RS Ophiuchi's eruption, identifying multiple temperature zones and estimating elemental abundances, which advances understanding of nova ejecta composition.

Findings

Detected rich emission line spectrum with fine structure and coronal lines.

Identified at least two temperature regions in the ejecta/wind environment.

Estimated the O/Ne abundance ratio to be greater than 0.6.

Abstract

We present Spitzer Space Telescope and complementary ground-based infrared observations of the recurrent nova RS Ophiuchi, obtained over the period 64-111 days after the 2006 eruption. The Spitzer IRS data show a rich emission line spectrum superimposed on a free-free continuum. The presence of fine structure and coronal infrared lines lead us to deduce that there are at least two temperatures (1.5e5K and 9e5K) in the ejecta/wind environment, and that the electron density in the `cooler' region is 2.2e5 cm-3. The determination of elemental abundances is not straightforward but on the assumption that the Ne and O fine structure lines arise in the same volume of the ejecta, the O/Ne ratio is >~0.6 by number.