2009/02/12 by E. Brandi, C. Quiroga, J. Mikolajewska +4 · 9 citations
Physics and Astronomy · #Absorption spectroscopy #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Orbit (dynamics) #Orbital elements #Orbital inclination #Orbital period #Radial velocity #Red giant #Spectral line #Stellar, planetary, and galactic studies #White dwarf #astro-ph.GA #astro-ph.SR
paper · pdf · doi:10.1051/0004-6361/200811417
12 pages, 10 figures, 4 tables. Astronomy & Astrophysics (accepted)
arxiv created 2009/02/12 · openalex publication_date 2009/02/18 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
<i>Aims. <i/>The aims of our study are to improve the orbital elements of the giant and to derive the spectroscopic orbit for the white dwarf companion of the symbiotic system RS Oph. Spectral variations related to the 2006 outburst are also studied.<i>Methods. <i/> We performed an analysis of about seventy optical and near infrared spectra of RS Oph that were acquired between 1998 and June 2008. The spectroscopic orbits were obtained by measuring the radial velocities of the cool component absorption lines and the broad H<i>α<i/> emission wings, which seem to be associated with the hot component. A set of cF-type absorption lines were also analyzed for a possible connection with the hot component motion. <i>Results. <i/>A new period of 453.6 days and a mass ratio, <i>q<i/> = <i>M<i/><sub>g<sub/>/<i>M<i/><sub>h<sub/> = 0.59 <i>±<i/> 0.05 were determined. Assuming a massive white dwarf as the hot component (<i>M<i/><sub>h<sub/> = 1.2-1.4 ) the red giant mass is <i>M<i/><sub>g<sub/> = 0.68-0.80 and the orbit inclination, = 49°-52°. The cF-type lines are not associated with either binary component, and are most likely formed in the material streaming towards the hot component. We also confirm the presence of the Li I doublet in RS Oph and its radial velocities fit very well to the M-giant radial velocity curve. Regardless of the mechanism involved to produce lithium, its origin is most likely from within the cool giant rather than material captured by the giant at the time of the nova explosion. The quiescent spectra reveal a correlation of the H I and He I emission line fluxes with the monochromatic magnitudes at 4800 Å, indicating that the hot component activity is responsible for those flux variations. We also discuss the spectral characteristics around 54–55 and 240 days after the 2006 outburst. In April 2006 most of the emission lines present a broad pedestal with a strong and narrow component at about -20 km s<sup>-1<sup/> and two other extended emission components at -200 and +150 km s<sup>-1<sup/>. These components could originate in a bipolar gas outflow supporting the model of a bipolar shock-heated shell expanding through the cool component wind perpendicularly to the binary orbital plane. Our observations also indicate that the cF absorption system was disrupted during the outburst, and restored about 240 days after the outburst, which is consistent with the resumption of accretion.