JWST MIRI MRS Observations of T Cha: Discovery of a Spatially Resolved Disk Wind

Abstract Understanding when and how circumstellar disks disperse is crucial to constrain planet formation and migration. Thermal winds powered by high-energy stellar photons have long been theorized to drive disk dispersal. However, evidence for these winds is currently based only on small (∼3–6 km s −1 ) blueshifts in Ne ii 12.81 μ m lines, which does not exclude MHD winds. We report JWST MIRI MRS spectro-imaging of T Cha, a disk with a large dust gap (∼30 au in radius) and blueshifted Ne ii emission. We detect four forbidden noble gas lines, Ar ii , Ar iii , Ne ii , and Ne iii , of which Ar iii is the first detection in any protoplanetary disk. We use line flux ratios to constrain the energy of the ionizing photons and find that argon is ionized by extreme ultraviolet, whereas neon is most likely ionized by X-rays. After performing continuum and point-spread function subtraction on the integral field unit cube, we discover a spatial extension in the Ne ii emission off the disk continuum emission. This is the first spatially resolved Ne ii disk wind emission. The mostly ionic spectrum of T Cha, in combination with the extended Ne ii emission, points to an evolved stage for any inner MHD wind and is consistent with the existence of an outer thermal wind ionized and driven by high-energy stellar photons. This work acts as a pathfinder for future observations aiming at investigating disk dispersal using JWST.