2MASS J05263562+0036016 , the SIMBAD biblio

We present a study of 15 new brown dwarfs belonging to the ∼ 7Myr old 25 Orionis group and Orion OB1a subassociation with spectral types between M6 and M9 and estimated masses between ∼ 0.07 and ∼ 0.01M_☉. By comparing them through a Bayesian method with low-mass stars (0.8 ≲ M/M_☉ ≲ 0.1) from previous works in the 25 Orionis group, we found statistically significant differences in the number fraction of classical T Tauri stars, Weak T Tauri stars, class II, evolved discs and purely photospheric emitters at both sides of the substellar mass limit. Particularly, we found a fraction of 3.9^+2.4_-1.6 percent low-mass stars classified as Classic T Tauri star and class II or evolved discs, against a fraction of 33.3^+10.8_-9.8 percent in the substellar mass domain. Our results support the suggested scenario in which the dissipation of discs is less efficient for decreasing mass of the central object.