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SY Cha is a T Tauri star surrounded by a protoplanetary disk with a large cavity seen in the millimeter continuum but has the spectral energy distribution of a full disk. Here we report the first results from JWST/Mid-InfraRed Instrument (MIRI) Medium Resolution Spectrometer (MRS) observations taken as part of the MIRI mid-INfrared Disk Survey (MINDS) GTO Program. The much improved resolution and sensitivity of MIRI-MRS compared to Spitzer enables a robust analysis of the previously detected H _2 O, CO, HCN, and CO _2 emission as well as a marginal detection of C _2 H _2 . We also report the first robust detection of mid-infrared OH and rovibrational CO emission in this source. The derived molecular column densities reveal the inner disk of SY Cha to be rich in both oxygen- and carbon-bearing molecules. This is in contrast to PDS 70, another protoplanetary disk with a large cavity observed with JWST, which displays much weaker line emission. In the SY Cha disk, the continuum, and potentially the line, flux varies substantially between the new JWST observations and archival Spitzer observations, indicative of a highly dynamic inner disk.

We present JWST-MIRI Medium Resolution Spectrometer (MRS) spectra of the protoplanetary disk around the low-mass T Tauri star GW Lup from the MIRI mid-INfrared Disk Survey Guaranteed Time Observations program. Emission from ^12 CO _2 , ^13 CO _2 , H _2 O, HCN, C _2 H _2 , and OH is identified with ^13 CO _2 being detected for the first time in a protoplanetary disk. We characterize the chemical and physical conditions in the inner few astronomical units of the GW Lup disk using these molecules as probes. The spectral resolution of JWST-MIRI MRS paired with high signal-to-noise data is essential to identify these species and determine their column densities and temperatures. The Q branches of these molecules, including those of hot bands, are particularly sensitive to temperature and column density. We find that the ^12 CO _2 emission in the GW Lup disk is coming from optically thick emission at a temperature of ∼400 K. ^13 CO _2 is optically thinner and based on a lower temperature of ∼325 K, and thus may be tracing deeper into the disk and/or a larger emitting radius than ^12 CO _2 . The derived ${N}_{{\mathrm{CO}}_{2}}$ / ${N}_{{{\rm{H}}}_{2}{\rm{O}}}$ ratio is orders of magnitude higher than previously derived for GW Lup and other targets based on Spitzer-InfraRed-Spectrograph data. This high column density ratio may be due to an inner cavity with a radius in between the H _2 O and CO _2 snowlines and/or an overall lower disk temperature. This paper demonstrates the unique ability of JWST to probe inner disk structures and chemistry through weak, previously unseen molecular features.