2016ApJ...820...53H

More than 40 years after the first discussion, the detection of a self-lensing phenomenon within a binary system where the brightness of a background star is magnified by its foreground companion was recently reported. It is expected that the number of self-lensing binary detections will be increased by a wealth of data from current and future survey experiments. In this paper, we introduce a degeneracy in the interpretation of self-lensing light curves. The degeneracy is intrinsic to self-lensing binaries for which both magnification by lensing and de-magnification by occultation occur simultaneously and are caused by the difficulty in separating the contribution of the lensing-induced magnification from the observed light curve. We demonstrate the severity of this degeneracy by presenting examples of self-lensing light curves that suffer from it. We also present the relation between the lensing parameters of the degenerate solutions. This degeneracy is an important obstacle in accurately determining self-lensing parameters and thus characterizing binaries.