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Arxiv: Precise Bolometric Luminosities and Effective Temperatures of 23 late-T and Y dwarfs Obtained with JWST Published: 7/11/2024 5:05:32 PM Updated: 7/18/2024 9:18:03 PM

Paper abstract: We present infrared spectral energy distributions of 23 late-type T and Ydwarfs obtained with the James Webb Space Telescope. The spectral energydistributions consist of NIRSpec PRISM and MIRI LRS spectra covering the~1--12 \mum wavelength range at \lambda/ \Delta \lambda ~ 100and broadband photometry at 15, 18, and 21 \mum. The spectra exhibitabsorption features common to these objects including H_2O, CH_4, CO,CO_2, and NH_3. Interestingly, while the spectral morphology changesrelatively smoothly with spectral type at \lambda < 3 \mum and \lambda >8 \mum, it shows no clear trend in the 5 \mum region where a largefraction of the flux emerges. The broad wavelength coverage of the data enablesus to compute the first accurate measurements of the bolometric fluxes of coolbrown dwarfs. Combining these bolometric fluxes with parallaxes from Spitzerand HST, we also obtain the first accurate bolometric luminosities of thesecool dwarfs. We then used the Sonora Bobcat solar metallicity evolutionarymodels to estimate the radii of the dwarfs which results in effectivetemperature estimates ranging from ~1000 to 350 K with a medianuncertainty of \pm20 K which is nearly an order of magnitude improvement overprevious work. We also discuss how various portions of the spectra either do ordo not exhibit a clear sequence when ordered by their effective temperatures.