Spectroscopic orbits and variations of RS Ophiuchi

Abstract

Aims. 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. Methods. 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 Hα 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. 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 −1 and two other extended emission components at −200 and +150 km s −1 . 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.

The spectroscopic evolution of the symbiotic-like recurrent nova V407 Cygni during its 2010 outburst

“…Although the UV flux was several orders of magnitude greater than a normal symbiotic star and the ionization was sufficient to produce the O VI FUV doublet, no O VI Raman emission was detected at either spectral region during the time interval covered by these observations. This contrasts with the RS Oph 2006 outburst during which the 6825 Å line was detected (Brandi et al 2009;Iijima 2009) in the early stages after outburst (before day 60). Brandi et al note that the line was absent in quiescence.…”

“…Recurrent novae are produced by the initiation of a thermonuclear runaway provoked by accretion on massive WDs, which are nearer to the Chandrasekhar limit (for RS Oph, M WD ≈ 1.2 M ) than for normal symbiotics or symbiotic novae (<1 M ) (see Starrfield 2008;Anupama 2008;Mikolajewska 2008;Brandi et al 2009). The connection of these systems, and their supersoft XR emission after outburst, to SN Ia progenitors has long been a scenario (e.g.…”

The Massive CO White Dwarf in the Symbiotic Recurrent Nova RS Ophiuchi

“…These results, however, are based on 1-2 lines only except for He and Fe, and it is not clear (no line profiles available) whether their spectra are representative for the ejecta. On the other hand, Brandi et al (2009) observed strong narrow-line components and a broad pedestal in all emission lines on highresolution optical spectra taken 53-54 days after the 2006 outburst maximum which means that by then the red giant wind contribution to the line emission became significant.…”

“…The supersoft phase exhibited by RS Oph also suggests that its WD is massive (Osborne et al 2011;Wolf et al 2013). RS Oph contains an M0-2 III mass donor (Dobrzycka et al 1996;Anupama & Miko lajewska 1999) in a binary with a 453.6 day orbital period (Brandi et al 2009). Brandi et al (2009) have presented compelling evidence for a massive WD in RS Oph.…”

“…RS Oph contains an M0-2 III mass donor (Dobrzycka et al 1996;Anupama & Miko lajewska 1999) in a binary with a 453.6 day orbital period (Brandi et al 2009). Brandi et al (2009) have presented compelling evidence for a massive WD in RS Oph. Seventy spectra, obtained over the decade 1998-2008 determined the orbital period to be 453.6 days, and a mass ratio q = M g /M h = 0.59 ± 0.05.…”