Fig. 10. H-R diagram for the Class III source with a known spectral types. Dotted lines show Palla & Stahler (1999) pre-main sequence tracks, continuous lines show isochrones. The bold continuous line represents the birthline for the star build-up accretion rate ( yr^-1). White dots show the position of Class III sources with known spectral type (Bouvier & Appenzeller 1992; Luhman & Rieke 1999; see also Greene & Meyer 1995), and using the Bontemps et al. (2000) luminosities. Crosses show X-ray detected Class III sources (Montmerle et al. 1983; CMFA; Koyama et al. 1994; Kamata et al. 1997; this article). We take pc. The error bar shows the systematic luminosity error corresponding to a distance error of pc.