# # Program information file # PROGRAM_ID 2024A055 PROGRAM_TITLE Testing Atmospheric Models with Hyades Brown Dwarfs PROGRAM_INV1 Robert Stiller PROGRAM_INV2 Michael Cushing PROGRAM_INV3 Adam Schneider PROGRAM_INV4 PROGRAM_INV5 PROGRAM_SCICAT stellar PROGRAM_ABSTRACT_BEG Our understanding of the formation and evolution of brown dwarfs hinges upon our ability to accurately determine their effective temperatures and surface gravities. This is typically accomplished by comparing atmospheric models to spectra and/or photometry in a least squares sense. Previous work has shown that models fail to accurately reproduce the observations but it is difficult to identify errors in the models because the least-squares fitting effectively averages out any differences between the data and models. If the age and luminosity of a brown dwarf are known, however, evolutionary models provide the effective temperature, and surface gravity and thus an atmospheric model with these parameters can be compared directly to the data. We propose to obtain SpeX prism spectra of 12 brown dwarfs in the Hyades cluster [650 Myr] in order to 1] compute their bolometric luminosities using the spectra and WISE W1 and W2 photometry, and 2] compare the corresponding atmospheric models directly to the data in order to identify errors in the atmospheric models. The observations will be obtained with the prism mode of SpeX using the 0.3 arcsecond-wide slit. PROGRAM_ABSTRACT_END