V2051 Ophiuchi after superoutburst: out-of-plane material and the superhump light source

Abstract

Aims. We performed a detailed spectroscopic analysis of the dwarf nova V2051 Oph at the end of its 1999 superoutburst. We studied and interpreted the simultaneous behaviour of various emission lines. Methods. We obtained high-resolution echelle spectroscopic data at ESO's NTT with EMMI, covering the spectral range of 4000-7500 Å. The analysis was performed using standard IRAF tools. The indirect imaging technique of Doppler tomography was applied, in order to map the accretion disc and distinguish between the different emission sources.Results. The spectra are characterised by strong Balmer emission, together with lines of He i and the iron triplet Fe ii 42. All lines are double-peaked, but the blue-to-red peak strength and central absorption depth vary. The primary's velocity was found to be 84.9 km s −1 . The spectrograms of the emission lines reveal the prograde rotation of a disc-like emitting region and, for the Balmer and He i lines, an enhancement of the red-wing during eclipse indicates a bright spot origin. The modulation of the double-peak separation shows a highly asymmetric disc with non-uniform emissivity. This is confirmed by the Doppler maps, which apart from the disc and bright spot emission also indicate an additional region of enhanced emission in the 4th quadrant (+V x , −V y ), which we associate with the superhump light source. Given the behaviour of the iron triplet and its distinct differences from the rest of the lines, we attribute its existence to an extended gas region above the disc. Its origin can be explained through the fluorescence mechanism.

Spiral structures and temperature distribution in the quiescent accretion disc of the cataclysmic binary V2051 Ophiuchi

“…In this way, we obtained the semi-amplitude for the primary component to be K1 = 84.4 km s −1 with the sample standard deviation 4.4 km s −1 . This value is in agreement with previous estimations by Baptista et al (1998), Papadaki et al (2008) and Longa-Peña, Steeghs & Marsh (2015). As the final value of φ0 we take the average of the cross-correlation and mirroring methods i.e.…”

“…The blue peak is the eclipse prior to the red peak. As was previously mentioned by Papadaki et al (2008), this indicates prograde rotation of the disc. There is no clear evidence of the S-wave and the overall structure of the trail spectra is quite complex, indicating the existence of multiple sources of emission.…”

“…Longa-Peña, Steeghs & Marsh (2015) carried out observations (JD 245 5386) ∼4 d after the outburst maximum when the system had ∼13.5 mag. Papadaki et al (2008) performed observations (JD 245 1394) around 8 d after the outburst maximum. During their observations, V2051 had 14.5-15.0 mag.…”

Structure of the pre-outburst accretion disk in SS Cygni

“…Another arm of the spiral tidal shock is invisible, although this may be because its radiation overlaps with the radiation of the bow shock (see the next paragraph). The tidal spirals are observed in a number of dwarf novae and resolved using Doppler tomography (Papadimitriou et al 2005;Papadaki et al 2008). In gas dynamical simulations, they were firstly reported in Sawada et al (1986).…”

Survey of period variations of superhumps in SU UMa-type dwarf novae. VIII. The eighth year (2015–2016)

“…In addition to above references, this object has been thoroughly investigated since it is fairly close and has received much attention from the early times: eclipse analysis (Baptista et al 1998;Vrielmann et al 2002;Papadaki et al 2008), flickering (Bruch 2000;Baptista, Bortoletto 2004), spectroscopy (Steeghs et al 2001;Saito, Baptista 2006;Longa-Peña et al 2015), and secular variation of the orbital period (Echevarria, Alvarez 1993;Baptista et al 2003). …”