Changes in the red giant and dusty environment of the recurrent nova RS Ophiuchi following the 2006 eruption

TL;DR

This study analyzes near-infrared spectra of RS Ophiuchi after its 2006 eruption, revealing variability in the red giant's atmosphere, dust emission, and the environment's evolution post-outburst.

Contribution

First detailed near-infrared spectral analysis of RS Oph post-2006 eruption, showing variability in dust and stellar atmosphere properties.

Findings

Red giant temperature estimated at 4200K.

Infrared excess from dust with temperature around 500K.

Dust emission was variable and undetectable in 2007.

Abstract

We present near infrared spectroscopy of the recurrent nova RS Oph obtained on several occasions after its latest outburst in 2006 February. The 1-5 mircon spectra are dominated by the red giant, but the H I, He I, and coronal lines present during the eruption are present in all our observations. From the fits of the computed infrared spectral energy distributions to the observed fluxes we find T_eff=4200+/-200,K for the red giant. The first overtone CO bands at 2.3 micron, formed in the atmosphere of the red giant, are variable. The spectra clearly exhibit an infrared excess due to dust emission longward of 5 micron; we estimate an effective temperature for the emitting dust shell of 500K, and find that the dust emission is also variable, being beyond the limit of detection in 2007. Most likely, the secondary star in RS Oph is intrinsically variable.