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Arxiv: The JWST Weather Report from the Isolated Exoplanet Analog SIMP 0136+0933: Pressure-Dependent Variability Driven by Multiple Mechanisms Published: 11/25/2024 7:06:16 PM Updated: 11/25/2024 7:06:16 PM

Paper abstract: Isolated planetary-mass objects share their mass range with planets but donot orbit a star. They lack the necessary mass to support fusion in their coresand thermally radiate their heat from formation as they cool, primarily atinfrared wavelengths. Many isolated planetary-mass objects show variations intheir infrared brightness consistent with non-uniform atmospheric featuresmodulated by their rotation. SIMP J013656.5+093347.3 is a rapidly rotatingisolated planetary-mass object, and previous infrared monitoring suggestscomplex atmospheric features rotating in and out of view. The physical natureof these features is not well understood, with clouds, temperature variations,thermochemical instabilities, and infrared-emitting aurora all proposed ascontributing mechanisms. Here we report JWST time-resolved low-resolutionspectroscopy from 0.8 - 11 micron of SIMP J013656.5+093347.3 which supports thepresence of three specific features in the atmosphere: clouds, hot spots, andchanging carbon chemistry. We show that no single mechanism can explain thevariations in the time-resolved spectra. When combined with previous studies ofthis object indicating patchy clouds and aurorae, these measurements reveal therich complexity of the atmosphere of SIMP J013656.5+093347.3. Gas giant planetsin the solar system, specifically Jupiter and Saturn, also have multiple cloudlayers and high-altitude hot spots, suggesting these phenomena are also presentin worlds both within and beyond our solar-system.