HRD of the Lupus association. Red squares and blue circles denote, respectively, the WTTSs and CTTSs in our sample. The green triangles represent those stars with transition disks (see Sect. 4). The error bars indicate the 1σ uncertainties on the stellar luminosities and effective temperatures. The black solid lines and dashed lines indicate, respectively, the evolutionary tracks and isochrones computed by Siess et al. (2000) with Y = 0.277 and Z = 0.02. The green solid line denotes the zero-age main sequence (ZAMS) computed with that model. The dash-dotted lines show the disk lifetime τ_d for the TTSs in the Lupus (this work) and Taurus-Auriga (Bertout et al. 2007) associations.