Clouds with a silicate lining: Using JWST spectra to probe atmospheric diversity in young AB Dor L dwarfs

We present the first full JWST NIRSpec Prism and MIRI LRS 0.6 -- 14 μm (R∼ 100) spectra and analysis of five ∼133,Myr L dwarf members of the AB Doradus moving group and one probable sim500,Myr T dwarf of the Oceanus moving group with known inclination angles between ∼ 23 -- ̧irc : , , , , , and . 0047 0355 0642 1741 2206 2244 We constructed near-complete spectral energy distributions of each of our objects to measure their bolometric luminosities, and we estimated their fundamental parameters (T_ eff , radius, M, and łog g). We used cross-sections of relevant gases to identify the species that are present in each atmosphere. Of particular interest is the silicate absorption feature at 8 -- 11 μm, which provides insight into the complex cloud structure of brown dwarfs. We examined this silicate absorption feature in detail and tested whether a latitudinal dependence exists in the silicate absorption feature within a coeval sample of brown dwarfs. Various molecular absorption bands are visible in our spectra, including , , CO, and . The shape of the silicate absorption feature varies within our sample, and we find that four out of five of our L type objects agree with previously observed trends, namely, that objects viewed equator-on have deeper silicate absorption. We highlight as an outlier in our sample with an unusually strong silicate absorption given its near pole-on orientation. We also present a tentative correlation between the wavelength of peak silicate absorption and inclination, which may suggest variations in cloud chemical composition or physical properties. h2o ch4 co2 1741 We found an unexpected spectral diversity within our sample, which motivates future studies on these objects through atmospheric retrievals, which will determine the silicate cloud composition and reveal whether there exists a trend with inclination.