H-R diagram for our sample, in comparison with theoretical evolutionary tracks. The figure shows absolute J-band magnitude vs. effective temperature, both listed in Table 1. We overplot error bars assuming errors of ±100 K in temperature and ±10% in brightness. The evolutionary tracks are from ATMO 2020 models (M. W. Phillips et al. 2020) for 0.005 and 0.01 M_⊙. The squares on the tracks mark ages of 1, 2, and 5 Myr, from top to bottom.