Luminous binary supersoft X-ray sources: Optical colors and absolute magnitudes

An analysis of the color indices and absolute magnitudes $M_{V0}$ of the “classical” supersoft X-ray binary sources (SSXBs), the V Sge-type stars (VSs), the symbiotic SSXBs, and the classical novae in the soft X-ray phase is presented. This approach can help comparing the properties and configuration of the reprocessing medium in the individual systems. The range of $M_{V0}$ of the individual objects is very large, from $M_{V0}=8.5$ to $M_{V0}=-4$, most systems having $M_{V0}<2$. The objects with the orbital period $P_{\rm orb}