# # Program information file # PROGRAM_ID 2022B100 PROGRAM_TITLE Using iSHELL to Explore Chemical Inheritance and Evolution in Young Stellar Objects PROGRAM_INV1 Rachel Smith PROGRAM_INV2 Adwin Boogert PROGRAM_INV3 PROGRAM_INV4 PROGRAM_INV5 PROGRAM_SCICAT stellar PROGRAM_ABSTRACT_BEG Observations of YSOs may be used to trace protoplanetary chemistry, and are analogues of the solar nebula. When the YSO environments are rich in CO, observations of isotopologues offer important comparisons with isotopic measurements in the oldest meteorites. With the very high spectral resolution of iSHELL, one can investigate the significance of variations in CO reservoirs as a function of time, as well as chemical inheritance through observations of YSOs in the same parent cloud. By obtaining precise isotope ratios of C and O via CO rovibrational spectroscopy, this project will help answer the following three questions: 1] How do the isotopic ratios of CO -- a critical carbon reservoir -- vary over time in YSOs? 2] Is there a dependency on the YSO environment? 3] How much do the isotope ratios vary among YSOs within the same molecular cloud and among disparate clouds? We plan to use IRTF-iSHELL at R~88,000 [M band] and R~78,000 [K band] to add statistical significance to the variable trends seen in previous work. We aim to build datasets to include at least four observations per target, as well as investigate variations between gravitationally bound binaries. For each of the three runs requested, the requested time is 135 min. of on-source time for the 6 targets in M1 mode and 120 min. on-source time in K3 mode, for a total [including overhead and the 3 runs] time request of 11.5 hours of time. We will rely on Spextool's Xtellcor_model in the reduction. We are requesting three half-night runs, with two of the runs spaced one- to two-days [max.] apart, and one run separated by at least one month. This will enable us to explore systematic and observational uncertainties. The run separated from the two paired runs would assess short-term variability in these targets. PROGRAM_ABSTRACT_END