A systematic study of spiral density waves in the accretion discs of cataclysmic variables

Abstract

Spiral density waves are thought to be excited in the accretion discs of accreting compact objects, including Cataclysmic Variable stars (CVs). Observational evidence has been obtained for a handful of systems in outburst over the last two decades. We present the results of a systematic study searching for spiral density waves in CVs, and report their detection in two of the sixteen observed systems. While most of the systems observed present asymmetric, non-Keplerian accretion discs during outburst, the presence of ordered structures interpreted as spiral density waves is not as ubiquitous as previously anticipated. From a comparison of systems by their system parameters it appears that inclination of the systems may play a major role, favouring the visibility and/or detection of spiral waves in systems seen at high inclination.

Spectroscopically Identified Cataclysmic Variables from the LAMOST Survey. II. Period Estimates

“…LAMOST J005347.32+405548.5. J005347 has been classified as dwarf nova, based on the photometric behaviors of its light curves from time-domain surveys, and labeled as U Gem in the VSX (Watson et al 2006;Coppejans et al 2016;Ruiz-Carmona et al 2020). Using the resulting light curves from the Catalina and PTF surveys, we obtain the same orbital period of 0.261602 days (6.278 hr), in agreement with the previous result (Ruiz-Carmona et al 2020).…”

New Spectroscopy of U Gem

“…While U Gem has been observed to show this structure in Doppler tomograms before (Neustroev & Borisov 1998;Unda-Sanzana et al 2006), the presence of fully formed spiral shocks in U Gem must be regarded with caution: the study of the evolution of spiral shocks in U Gem performed by Groot (2001) shows that they fade during the decline of the outburst. And even if spi-ral arms were present in U Gem in quiescence, they would be expected to be tightly wrapped during this stage (Steeghs & Stehle 1999); hence very difficult to detect with Doppler tomography (Ruiz-Carmona et al 2020). As discussed by Unda-Sanzana et al (2006), the spiral feature in the tomography could instead be explained by irradiation from the WD of regions of the disc that become thickened from tidal distortion.…”