2018/10/08 by Min Fang, Ilaria Pascucci, Suzan Edwards +7 · 117 citations
Physics and Astronomy · #Accretion (finance) #Astro and Planetary Science #Astrophysics #Astrophysics and Star Formation Studies #Atomic physics #Excited state #Geometry #Lambda #Line (geometry) #Magnetohydrodynamic drive #Magnetohydrodynamics #Mechanics #Nuclear physics #Optics #Physics #Plasma #Shock (circulatory) #Stars #Stellar, planetary, and galactic studies #T Tauri star #Terminal velocity #astro-ph.SR
paper · pdf · doi:10.3847/1538-4357/aae780
published in The Astrophysical Journal 868(1), 28 (IOP Publishing) · 45 pages, 23 figures, and 7 tables, accepted by ApJ
arxiv created 2018/10/08 · openalex publication_date 2018/11/15 · arxiv updated 2018/11/28 · openalex created_date 2020/11/23 · openalex updated_date 2026/08/08
Abstract Magnetohydrodynamic (MHD) and photoevaporative winds are thought to play an important role in the evolution and dispersal of planet-forming disks. We report the first high-resolution (Δ v ∼ 6 km s −1 ) analysis of [S ii ] λ 4068, [O i ] λ 5577, and [O i ] λ 6300 lines from a sample of 48 T Tauri stars. Following Simon et al. we decompose them into three kinematic components: a high-velocity component (HVC) associated with jets, and low-velocity narrow (LVC-NC) and broad (LVC-BC) components. We confirm previous findings that many LVCs are blueshifted by more than 1.5 km s −1 and thus most likely trace a slow disk wind. We further show that the profiles of individual components are similar in the three lines. We find that most LVC-NC and LVC-BC line ratios are explained by thermally excited gas with temperatures between 5000 and 10,000 K and electron densities of ∼10 7 –10 8 cm −3 . The HVC ratios are better reproduced by shock models with a pre-shock H number density of ∼10 6 –10 7 cm −3 . Using these physical properties, we estimate for the LVC and for the HVC. In agreement with previous work, the mass carried out in jets is modest compared to the accretion rate. With the likely assumption that the LVC-NC wind height is larger than the LVC-BC, the LVC-BC is found to be higher than the LVC-NC. These results suggest that most of the mass loss occurs close to the central star, within a few au, through an MHD-driven wind. Depending on the wind height, MHD winds might play a major role in the evolution of the disk mass.