Dr. Emma Whelan

Maynooth University, Ireland

Searching for an MHD Disk Wind Component via Optical Forbidden Emission Line Spectro-astrometry

Abstract: A crucial step in understanding how stars accrete their mass, as well as how disks evolve, is clarifying how the accreting disk gas loses angular momentum with both MHD disk winds and MRI induced turbulence explored. Recent simulations find that non-ideal MHD effects suppress MRI over a large range of disk radii, restoring radially extended MHD disk winds as the prime means for extracting angular momentum and enabling accretion at the observed rates. On the observational side, there has been renewed interest in identifying disk wind tracers and testing the emerging paradigm of disk evolution. Emission from optical forbidden lines has been a long-established tracer of flowing material from young stars with the low velocity component of emission region thought to trace the disk wind component of the flow. Here I report the results of a study which used spectro-astrometry to disentangle the origin of the [O I]6300 and [S II]6731 low velocity component in a sample of T Tauri stars. Particular goals were to understand if the low velocity narrow and broad components have different origins and to constrain the mass outflow to accretion rates in any wind component identified.