# # Program information file # PROGRAM_ID 2023A012 PROGRAM_TITLE Characterizing Cool Hosts of Candidate Transiting Exoplanets with IRTF/SpeX PROGRAM_INV1 Benjamin Rackham PROGRAM_INV2 Adam Burgasser PROGRAM_INV3 PROGRAM_INV4 PROGRAM_INV5 PROGRAM_SCICAT extra-solar planets PROGRAM_ABSTRACT_BEG Planetary transits of cool dwarfs [T_eff < 3900 K] provide our only opportunity to characterize terrestrial exoplanets in detail in the next 20 years. The Transiting Exoplanet Survey Satellite [TESS] is leading the way in discovering planets transiting cool dwarfs, with 68 confirmed since its 2018 launch. However, many more await confirmation, and the lack of archival spectra suitable for stellar characterization for many cool TESS Objects of Interest [TOIs] is a significant bottleneck. Here we propose to address this need by collecting medium-resolution NIR spectra of 75 cool TOIs with SpeX/IRTF. This program will provide a critical input for the confirmation of dozens of new transiting exoplanet systems that are prime targets for future in-depth characterization. These spectra will allow us to probe binarity, assign spectral types, and measure strengths of molecular bands and equivalent widths of atomic lines for each of our targets, providing useful discriminators of temperature, mass, gravity, metallicity, and condensation chemistry. Along with SOAR/TripleSpec4.1 spectra from a complementary effort in the south, the reduced spectra will be made publicly accessible on the Exoplanet Follow-up Observing Program for TESS [ExoFOP-TESS] website, supporting both discovery papers led by our team as well as those from the wider community. PROGRAM_ABSTRACT_END