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Arxiv: A Disintegrating Rocky World Shrouded in Dust and Gas: Mid-IR Observations of K2-22b using JWST Published: 1/14/2025 8:31:15 PM Updated: 1/14/2025 8:31:15 PM

Paper abstract: The disintegrating ultra-short period rocky exoplanet K2-22b periodicallyemits dusty clouds in a dynamically chaotic process resulting in a variabletransit depth from 0-1.3%. The effluents that sublimate off the surface andcondense out in space are probably representative of the formerly interiorlayers convectively transported to the molten surface. Transmissionspectroscopy of these transiting clouds reveal spectral fingerprints of theinterior composition of this rocky world. We used JWST's Mid-InfraredInstrument (MIRI) as a low-resolution slitless spectrograph to observe fourpredicted transit windows for K2-22b. For each observation, we extracted atransmission spectrum over the spectral range of 4.3-11.8 \mum. We detect onetransit at high significance and two at low significance. We find that the data1) disfavor featureless, iron-dominated core material, 2) are consistent withsome form of magnesium silicate minerals, likely from mantle material, and 3)show a distinct and unexpected feature at ~5 \mum. The unexpectedfeature, also seen weakly in the low-significance transits, is consistent withsome gas features, possibly NO and/or CO_2. These findings warrant furtherstudy to improve the constraints on the composition of this disintegratingrocky world.