2015/04/20 by Juan José Downes, C. Román-Zúñiga, Carlos Román-Zúñiga +21
Physics and Astronomy · #Astro and Planetary Science #Astrophysics and Star Formation Studies #FOS: Physical sciences #Solar and Stellar Astrophysics (astro-ph.SR) #Stellar, planetary, and galactic studies #astro-ph.SR
paper · pdf · doi:10.48550/arxiv.1504.05196
Accepted for publication in Monthly Notices of the Royal Astronomical Society. 15 pages, 9 figures and 5 tables
arxiv created 2015/04/20 · openalex publication_date 2015/04/20 · arxiv updated 2015/04/22 · openalex created_date 2022/10/01 · openalex updated_date 2026/07/28
We present a study of 15 new brown dwarfs belonging to the ∼7 Myr old 25 Orionis group and Orion OB1a sub-association with spectral types between M6 and M9 and estimated masses between ∼0.07M_\odot and ∼0.01 M_\odot. By comparing them through a Bayesian method with low mass stars (0.8\lesssim M/M_\odot\lesssim0.1) 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 sub-stellar mass limit. Particularly we found a fraction of 3.9+2.4-1.6~% low mass stars classified as CTTS and class II or evolved discs, against a fraction of 33.3+10.8-9.8~% in the sub-stellar mass domain. Our results support the suggested scenario in which the dissipation of discs is less efficient for decreasing mass of the central object.