Probing Protoplanetary Disk Winds with C II Absorption

Kavli Affiliate: Gregory J. Herczeg

| First 5 Authors: Ziyan Xu, Gregory J. Herczeg, Christopher M. Johns-Krull, Kevin France,

| Summary:

We present an analysis of wind absorption in the C II ${lambda}1335$ doublet
towards 40 classical T Tauri stars with archival far-ultraviolet (FUV) spectra
obtained by the Hubble Space Telescope. Absorption features produced by fast or
slow winds are commonly detected (36 out of 40 targets) in our sample. The wind
velocity of the fast wind decreases with disk inclination, consistent with
expectations for a collimated jet. Slow wind absorption is detected mostly in
disks with intermediate or high inclination, without a significant dependence
of wind velocity on disk inclination. Both the fast and slow wind absorption
are preferentially detected in FUV lines of neutral or singly ionized atoms.
The Mg II ${lambda}{lambda}2796,2804$ lines show wind absorption consistent
with the absorption in the C II lines. We develop simplified semi-analytical
disk/wind models to interpret the observational disk wind absorption. Both fast
and slow winds are consistent with expectations from a thermal-magnetized disk
wind model and are generally inconsistent with a purely thermal wind. Both the
models and the observational analysis indicate that wind absorption occurs
preferentially from the inner disk, offering a wind diagnostic in complement to
optical forbidden line emission that traces the wind in larger volumes.

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