Our T Tauri sample set in the Hertzsprung-Russell diagram. The colors of the symbols denote the star forming regions. Dashed blue lines denote the isochrones for 1, 2, 3, 5, 10, 12, and 100 Ma, and solid gray lines the iso-mass tracks from 0.6 to 3 M_⊙. The tracks are PMS PISA tracks (Tognelli et al. 2011) for solar abundances (Z = 0.02 and Y = 0.288), a solar-calibrated mixing length (α = 1.68), and an initial deuterium abundance of 2 × 10⁻⁵. The circles denote the fully convective stars, while the triangles denote the stars with a radiative core and a convective envelope.