Many intermediate-mass close binaries exhibit photometric cycles longer than their orbital periods, likely linked to variations in their accretion disks. Previous studies suggest that analyzing historical light curves provides key insights into disk evolution and may help track changes in mass transfer rates in such systems. Our research explores short- and long-term fluctuations in the eclipsing system ̌ar, focusing on the variability of its long cycle. We aim to clarify the role of the accretion disk in these modulations, especially those spanning hundreds of days, and to determine the system's evolutionary status to better understand its stellar components. We analyzed 32. 3 years of photometric time series from the Optical Gravitational Lensing Experiment (OGLE) in the I and V bands, and from the MAssive Compact Halo Objects (MACHO) project in BM and RM bands. Using data from multiple epochs, we modeled the accretion disk across 20 equally spaced phases of the long cycle. To solve the inverse problem, we implemented an optimized simplex algorithm to determine the best parameters for the stars, their orbit, and the disk. The Modules for Experiments in Stellar Astrophysics () code was employed to assess the system's evolutionary stage and predict its past and future development. MESA We find an orbital period of 6 and a long cycle of 229 Our orbital solutions reproduce the light curves, but the quasi-conservative mass transfer scenario yields rates that are too high for the orbital period stability. We find a consistency with the observed orbital-to-long-period ratio under the magnetic dynamo hypothesis. The normalized mass transfer rate follows the long cycle, reaching a maximum when brightness is minimum. At that phase, the disk's inner edge thickens, obscuring more of the gainer star. Disk variability mainly occurs in its vertical extension, with a standard deviation of 69% the mean value at the inner border, with minor changes in the outer radius and temperature of 7% and 5%, respectively.
Mennickent et al. (Fri,) studied this question.