IRTF Data Archive Program Information

# # Program information file # PROGRAM_ID 2022A036 PROGRAM_TITLE C/O ratio of M stars with T-dwarf companions PROGRAM_INV1 Josefine Gaarn PROGRAM_INV2 Ben Burningham PROGRAM_INV3 Jackie Faherty PROGRAM_INV4 Daniella Bardalez Gagliuffi PROGRAM_INV5 PROGRAM_SCICAT stellar PROGRAM_ABSTRACT_BEG The composition of a brown dwarf provides clues to its formation mechanism, as the composition will differ depending on the timescale over which it formed. Brown dwarfs are generally thought to form like stars, but the lowest mass ones may have formed like planets in a circumstellar disk. This thesis will investigate formation scenarios of brown dwarfs, both field objects and objects in systems, by comparing their C/O ratio. For brown dwarfs in systems, this also involves comparing their C/O ratio of their primary stars. For this we require high resolution spectra to measure the CO and H2O abundances of the primary stars. We focus on companion T-dwarfs of spectral type T5 or later, due to the relative ease of retrieving abundances in atmospheric retrieval studies. Three primaries to T5-dwarfs or later have been selected, with the primaries all being M-dwarfs. We propose a half night [about 5 hours] with the iSHELL instrument on the IRTF in order to obtain high-resolution spectra of the three selected M-dwarfs, plus a calibration M-dwarf, of which the abundance is known, in order to ensure that method for getting composition is correct. Previous data has been obtained with iSHELL for four primary stars to late T-dwarfs and three calibration targets. PROGRAM_ABSTRACT_END