Aarhus Universitets segl

New center article - Ewine van Dishoeck

Title: MINDS. The detection of 1313CO22 with JWST-MIRI indicates abundant CO22 in a protoplanetary disk

We present JWST-MIRI MRS spectra of the protoplanetary disk around the low-mass T Tauri star GW Lup from the MIRI mid-INfrared Disk Survey (MINDS) GTO program. Emission from 1212CO22, 1313CO22, H22O, HCN, C22H22, and OH is identified with 1313CO22 being detected for the first time in a protoplanetary disk. We characterize the chemical and physical conditions in the inner few au 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 1212CO22 emission in the GW Lup disk is coming from optically thick emission at a temperature of ∼∼400 K. 1313CO22 is optically thinner and based on a lower temperature of ∼∼325 K, may be tracing deeper into the disk and/or a larger emitting radius than 1212CO22. The derived NCO2/NH2O ratio is orders of magnitude higher than previously derived for GW Lup and other targets based on \textit{Spitzer}-IRS data. This high column density ratio may be due to an inner cavity with a radius in between the H22O and CO22 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.

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