# # Program information file # PROGRAM_ID 2024B008 PROGRAM_TITLE Cosmic-ray processing of interstellar ice towards supernova remnant W44 PROGRAM_INV1 Tianyu Tu PROGRAM_INV2 Yang Chen PROGRAM_INV3 PROGRAM_INV4 PROGRAM_INV5 PROGRAM_SCICAT galactic/interstellar medium PROGRAM_ABSTRACT_BEG Cosmic rays [CRs] have strong influence on the chemistry of interstellar ice. However, despite great importance, observational studies are still scarce, especially towards line of sights with enhanced CR flux. In this proposal, we plan to observe simultaneously the H2O, CH3OH and CO ice absorption with IRTF/SpeX against 5 stars associated with supernova remnant [SNR] W44, which is believed to be an accelerator of CRs and to be interacting with a molecular cloud complex. The target stars are chosen to be bright in 4.6um band and to be most likely absorbed by MCs associated with W44. We will use the strategies of previous studies to obtain the optical depths, column densities [or corresponding upper limits] of H2O, CH3OH and CO, as well as the best-fit extinction. The proposed observation can help us study the following two issues: [1] formation of CH3OH ice by energetic processing, through the comparison of the observed abundance ratios N[CH3OH]/N[H2O] and N[CH3OH]/N[CO] with typical values, and [2] destruction of ice by CR bombardment, through the comparison of the observed relation between ice column densities and extinction with previous results. The results will also be compared with chemical simulations to better understand the chemistry and identify the defects of chemical models. This observation will not only help us understanding the CR processing of dust mantles, but also open a new window to study the SNR feedback. Concerning the required time, we request a signal-to-noise ratio of >100 in M band to search for CO absorption. The total itime is multiplied by 2 to obtain the clock time which includes the time for default NDRs, and extra time is added to account for other overheads. We require 11 hours in total for the observation. PROGRAM_ABSTRACT_END