# # Program information file # PROGRAM_ID 2024A035 PROGRAM_TITLE Characterizing Color Outlier Ultracool Dwarfs PROGRAM_INV1 Austin Rothermich PROGRAM_INV2 Jacqueline Faherty PROGRAM_INV3 Emily Calamari PROGRAM_INV4 Les Hamlet PROGRAM_INV5 Tom Bickle PROGRAM_SCICAT stellar PROGRAM_ABSTRACT_BEG Low mass stars and brown dwarfs, together referred to as ultracool dwarfs, serve as an excellent analog for the study of exoplanet atmospheres, as the two populations overlap in temperature and are therefore subject to similar atmospheric processes. While there have been many advances in the understanding of low temperature atmospheres, the effects of surface gravity, metallicity, and clouds on the observed spectral energy distributions of ultracool dwarfs remain a challenge to model. It has been generally observed that younger, cloudier objects appear to have redder infrared colors, while the colors of lower metallicity objects appear bluer. Studying these red and blue color outliers therefore presents an opportunity to untangle how these properties interplay with one another, allowing for a better understanding of their effects in cool atmospheres. In this IRTF proposal, we propose to obtain near infrared spectra of 34 unusually red and blue brown dwarfs which bookmark the extremes of atmosphere, metallicity and gravity properties. With a moderate S/N of 20-30, we will be able to confirm the ultracool dwarf nature of the objects, as well as search for spectral features indicative of age, metallicity, and atmospheric conditions PROGRAM_ABSTRACT_END