Distribution of α_IRAC for sources in the IRAC sample (open histogram) and for 349 candidate members previously identified by Fűrész et al. (2006) (hatched-line histogram). The small inset is the same diagram but zoomed into the α_IRAC region corresponding to sources with thick disks. The shaded areas correspond to the regions in the histograms occupied by Class I (C I) sources, flat spectrum (FS) sources, sources with thick disks (TD), sources with anaemic disks (AD), and sources with naked photospheres (NP).