Abstract
The eclipsing system OGLE-SMC-ECL-0277 was found to exhibit unusual photometric variability. Beside its eclipsing nature additional variations with the periodicity of about 1500 d are also seen.
Variations of the eclipse depth during the time span of the observational data (mainly taken from the OGLE survey, partly our new ones) are the most pronounced. The complex behavior of all these changes makes this system absolutely unique, no such variability was ever detected and studied in other systems before.
Hence, are there some new phenomena, new physics or an unknown effects playing a role? We tried to understand these variations using four different hypotheses (i.e., inclination change, spot evolution, and/or pulsation of one or both components) and comparing their results we discussed which of them is the most likely. Neither of the presented hypotheses is able to describe in detail the behavior of OGLE-SMC-ECL-0277.
We also discuss a possibility that the variable can be a member of the so-called double periodic variables group.