Color-magnitude diagrams, considering only Pan-STARRS and DECam counterparts (gray background points) of X-ray sources classified as stars according to Criterion 2 (see Sect. 2.5.2). As a comparison, we overplot isochrones with different ages (from log(Age)  =  7.0 − 10.0) taken from the MIST package (Dotter 2016; Choi et al. 2016). Each panel represents different metallicities (from [Fe/H]  =   − 3.0 to +0.5), while solid and dashed lines are isochrones with attenuations of A_V  =  0.0 and 5.0, respectively.