# # Program information file # PROGRAM_ID 2021A072 PROGRAM_TITLE Eclipsing binary brown dwarf candidates in NGC 2264 PROGRAM_INV1 Samuel Pearson PROGRAM_INV2 Aleks Scholz PROGRAM_INV3 PROGRAM_INV4 PROGRAM_INV5 PROGRAM_SCICAT stellar PROGRAM_ABSTRACT_BEG We propose to obtain low-resolution IR spectra of four eclipsing binary brown dwarf candidates in NGC 2264. With this data we can estimate the spectral type, temperature and luminosity of the primary, look for the spectroscopic signatures of youth, and thus establish them as substellar members of NGC 2264. Theoretical evolution models are typically relied upon to infer masses, radii and ages of brown dwarfs, as these properties are notoriously difficult to measure. Constraining these models is key to our understanding of brown dwarf evolution. Eclipsing binary brown dwarfs can provide empirical measurements of brown dwarf properties that can be used to benchmark the theoretical evolution models. To date, only 2 eclipsing brown dwarf binaries are known. The four brown dwarf candidates were identified as eclipsing binaries by their light curves as part of our deep survey of NGC 2264 [S Pearson et al. 2020]. Our candidates fall into the magnitude range from K = 14.1 to K = 16.2. To achieve a signal-to-noise ratio of > 10 requires an on-source time of between 1 − 20 minutes for each of our targets. This signal-to-noise will be sufficient to fit the continuum of the spectra to template spectral standards, in order to determine the spectra types of our targets. Due to the highly variable nature of our targets, we propose to observe each source at two epochs. This will increase the likelihood of obtaining a spectra for each source while it is not eclipsing. In total we ask for two hours of telescope time, split over two nights. PROGRAM_ABSTRACT_END