# # Program information file # PROGRAM_ID 2024A082 PROGRAM_TITLE SpeX NIR spectroscopy of Infant Type Ia supernovae PROGRAM_INV1 Melissa Shahbandeh PROGRAM_INV2 Eric Hsiao PROGRAM_INV3 David Sand PROGRAM_INV4 Mark Phillips PROGRAM_INV5 Ori Fox PROGRAM_SCICAT extra-galactic PROGRAM_ABSTRACT_BEG Six classically scheduled half nights with SpeX are requested to obtain high S/N NIR spectra of infant Type Ia supernovae [SNe Ia] hours to days after the explosion and to follow them as they evolve. This SpeX program will be integral to an intensive observing campaign using several follow-up resources. The advent of improved wide-field transient searches, a machine learning-based alert broker, and multi-color pre-screening high-cadence photometry will ensure a high likelihood of very young SNe Ia. This program aims to obtain an unprecedented data set of early-time spectra and photometry to investigate the origins and mechanisms of SNe Ia. Very early-time spectra can be used to measure the ejecta's outer layers and distinguish between the ``explosion mechanisms and progenitor scenarios. For example, Chandrasekhar-mass delayed detonation and sub-Chandrasekhar-mass double detonation scenarios have very different predictions for the amount and velocity of unburned carbon remaining in the very outer layer, which is most effectively studied in the early NIR C I 1.0693-micron line. PROGRAM_ABSTRACT_END