VY Scl-type cataclysmic variable SDSS J154453.60+255348.8: stellar and disc parameters

We present a new study of the eclipsing cataclysmic variable SDSS J154453.60+255348.8 to determine the object's nature and its system parameters together with the probe of the accretion flow structure in the system. Based on analyses of new simultaneous time-resolved photometric and spectroscopic observations of SDSS J154453.60+255348.8 and using our light-curve modelling techniques and the Doppler tomography method, we found that the system contains a white dwarf with the mass of M-WD = 0.62(7) M-circle dot and an evolved red dwarf as a secondary. The system inclination is close to 90 degrees and the mass ratio is q = 0.49(2). The secondary has an effective temperature T-2 = 3400(40) K and a radius about 1.35(15) times larger than a zero-age main-sequence star with similar mass. From observation of the system in high- and low-brightness states, we conclude that SDSS J154453.60+255348.8 is a long-orbital period VY Scl-type system. The accretion disc in the high state is about two times less than the truncation radius, and is completely missing during the low state of the system.

Automated summary

In this study, we analyzed new observational data of SDSS J154453.60+255348.8 to determine its nature and system parameters. We found that the system consists of a white dwarf with a mass of 0.62 solar masses and an evolved red dwarf as a secondary. The system has a high inclination angle of close to 90 degrees and a mass ratio of 0.49. The observations of the system in high- and low-brightness states led us to conclude that it is a VY Scl-type system with a long orbital period, and the accretion disc is significantly different in the two states.