IP Pegasi: Investigation of the accretion disk structure

Abstract

Abstract. We present the results of spectral investigations of the cataclysmic variable IP Peg in quiescence. Optical spectra obtained on the 6-m telescope at the Special Astrophysical Observatory (Russia), and on the 3.5-m telescope at the GermanSpanish Astronomical Center (Calar Alto, Spain), have been analysed by means of Doppler tomography and Phase Modelling Technique. From this analysis we conclude that the quiescent accretion disk of IP Peg has a complex structure. There are also explicit indications of spiral shocks. The Doppler maps and the variations of the peak separation of the emission lines confirm this interpretation. We have detected that all the emission lines show a rather considerable asymmetry of their wings varying with time. The wing asymmetry shows quasi-periodic modulations with a period much shorter than the orbital one. This indicates the presence of an emission source in the binary rotating asynchronously with the binary system. We also have found that the brightness of the bright spot changes considerably during one orbital period. The spot becomes brightest at an inferior conjunction, whereas it is almost invisible when it is located on the distant half of the accretion disk. Probably, this phenomenon is due to an anisotropic radiation of the bright spot and an eclipse of the bright spot by the outer edge of the accretion disk.

Voracious vortexes in cataclysmic variables

“…For example, the disc in VW Hyi appears slightly larger than the tidal radius r max (Smith et al 2006), whereas in WZ Sge, V406 Vir, EZ Lyn, and the old nova RR Pic, the disc radius was shown to be no smaller than the 3:1 resonance radius Aviles et al 2010;Zharikov et al 2013;Schmidtobreick et al 2008). The disc radius of IP Peg, as estimated from the double-peaked emission line profiles (∼570 km s −1 - Neustroev et al 2002), also appears to be a bit larger than the tidal truncation radius (0.45 ± 0.05a and 0.40a, respectively).…”

“…Examples of the application of this technique to the real data are given in Neustroev (1998), Neustroev et al (2002Neustroev et al ( , 2014. References.…”

Doppler tomography of cataclysmic variables

“…In the case of WZ Sge the spectra were all taken during the same high state (as this system only outbursts every 20-30 years) whereas for IP Peg the structure has been seen in three different outbursts and for U Gem in two. For IP Peg and U Gem some authors have also found indication of spiral structure during quiescence (IP Peg: Neustroev et al 2002, U Gem: Unda-Sanzana et al, in press, see Fig. 1).…”

“…The spiral structure not only varies in strength but also in size and position in the disc (Boffin & Steeghs 2002). Also of interest are the maps of helium CVs like AM CVn, that allowed the authors to constrain the system parameters (Nelemans et al 2001) and GP Com, that showed a rather complicated structure in the bright spot emission (Morales-Rueda et al 2003), maps of IP Peg during quiescence possibly showing the pres-ence of spiral structure (Neustroev et al 2002), and maps of magnetic systems that allowed the authors to constrain the accretion geometry (Schwope 2001).…”

“…Marsh 1988. On the other hand, Neustroev et al (2002) and UndaSanzana et al (in press) find indications of the presence of spiral structure in the discs of IP Peg and U Gem respectively during quiescence (see Fig. 1).…”