Near-infrared color–color diagram of the know (blue) and new (red) ρ Oph sources, including the control sample in gray and the sources from the second population (Pop 2) as black symbols, using the J, H and K_S passbands from 2MASS. The main sequence and the giant branches from Bessell & Brett (1988) are included in the diagram, as well as an extinction vector in the K_S passband, labeled as A_K. The two parallel lines with the slope of the extinction vector enclose sources that are reddened mainly due to extinction in this color space.