# # Program information file # PROGRAM_ID 2024A986 PROGRAM_TITLE The NIR Lifetimes of Type Ia Supernovae Viewed Through Spectroscopy PROGRAM_INV1 David Jones PROGRAM_INV2 PROGRAM_INV3 PROGRAM_INV4 PROGRAM_INV5 PROGRAM_SCICAT extra-galactic PROGRAM_ABSTRACT_BEG The last decade of new, low-redshift time-domain surveys has revolutionized the study of Type Ia supernovae (SNe Ia) and cosmological parameter inference. However, comparatively little data are obtained in the near-infrared (NIR), where SN Ia spectra are sensitive to nucleosynthetic yields of Sne and cosmological parameter inferences are less affected by systematic errors due to dust. With IRTF, we propose a survey to obtain spectral sequences for a sample of NIR-observed SNe. With these data, we will determine the outer edge of nickel in the SN with a near-peak spectrum, and combine those data with early-time spectra from an active Gemini program to constrain the presence of unburned carbon in the ejecta. With simultaneous NIR photometry, optical photometry, and optical spectroscopy from UKIRT and UH88, we will obtain a holistic view of each SN explosion. We will reduce systematic uncertainties on cosmological parameter measurements by constraining the dust reddening curve for each SN and constraining the variation in reddening laws along the lines of sight to SNe Ia. The primary goal of this proposal is to drastically increase the available high-quality early-time NIR SN Ia sample in 2024A, with a larger sample assembled over future semesters. Simultaneously, we will obtain NIR observations of a number of core-collapse SNe in order to better understand dust formation and interactions with the nearby circumstellar medium. PROGRAM_ABSTRACT_END