The JWST Benchmark Brown Dwarf Library

Le résumé fourni par la source

With masses below the hydrogen burning mass limit, brown dwarfs are not able to generate stable fusion within their cores, thus never forming a main sequence. Instead, they slowly cool and contract as they age, resulting in a degeneracy between their fundamental parameters such as age, luminosity, and mass. Combined with the diverse array of molecular and condensate species present in their atmospheres, which produce complex emergent spectra, a complete characterization of brown dwarf fundamental properties remains elusive. While most brown dwarfs are found in isolation, a small subset have been found as companions to higher mass stars, referred to as “benchmarks”. Assuming coevality between the pair, properties which are more easily obtained for the host star, such as age and composition, can be applied to the brown dwarf companion, thus forming an ideal sample with which to inform and test current atmospheric models. In this presentation, we present the full 0.8-14 um spectral energy distributions (SEDs) from JWST for 12 benchmark systems, with spectral types L0-T5 and each a companion to an FGK type star which provides precise ages and elemental abundances. Using high signal to noise (SNR) broadband SEDs for the ultracool dwarf companions, we semi-empirically derive each benchmark’s bolometric luminosity (Lbol) and effective temperature (Teff), and compare molecular absorption strengths with one another. Our analysis is grounded using the elemental abundances from each source’s host star. Finally, we investigate the emergence, and subsequent removal, of silicate condensates within brown dwarf atmospheres. We will present comparisons of the 8-11 micron feature, placing morphological differences into context with their ages and compositions. These JWST benchmark spectra establish a new empirical reference for brown dwarf atmospheres, enabling stringent tests of cloud physics, chemistry, and evolutionary models

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.