High-resolution optical spectroscopy of RS Ophiuchi during 2008 -- 2009

TL;DR

This study provides the most detailed high-resolution spectroscopic observations of RS Ophiuchi over one orbital cycle, revealing complex line profiles, a tidally locked red giant, and circumbinary material shaped by past nova outbursts.

Contribution

It offers the first comprehensive high-resolution spectral dataset of RS Oph during quiescence, with detailed analysis of line profiles, stellar rotation, and circumbinary features.

Findings

No direct accretion disc signatures detected.

Red giant is tidally locked to the orbit.

Circumbinary medium shows Na I absorption features.

Abstract

RS Ophiuchi is a symbiotic variable and a recurrent nova. We have monitored it with the Nordic Optical Telescope and obtained 30 high resolution (R=46 000) optical spectra over one orbital cycle during quiescence. To our knowledge this is the best-sampled high resolution spectroscopic dataset of RS Oph over one orbital period. We do not detect any direct signatures of an accretion disc such as double peaked emission lines, but many line profiles are complex consisting of superimposed emission and absorption components. We measure the spin of the red giant and conclude that it is tidally locked to the binary orbit. We observe Na I absorption features, probably arising from the circumbinary medium, that has been shaped by previous recurrent nova outbursts. We do not detect any intrinsic polarisation in the optical wavelengths.