# # Program information file # PROGRAM_ID 2021B126 PROGRAM_TITLE Using iSHELL to Investigate Short-term Variability in Young Stellar Objects Across the Galaxy PROGRAM_INV1 Rachel Smith PROGRAM_INV2 Adwin Boogert PROGRAM_INV3 PROGRAM_INV4 PROGRAM_INV5 PROGRAM_SCICAT stellar PROGRAM_ABSTRACT_BEG This project aims to maximize the high spectral resolution of IRTF-iSHELL [R~80,000] to explore carbon and oxygen in YSOs at a range of R_GC and environments[i.e. varying UV fluxes and presence of a binary companion]. The high spectral resolution of iSHELL and the size and location of IRTF are uniquely suited for enabling precise derivations of column densities and temperatures along a single line of sight for massive YSOs, yielding meaningful comparisons with solar-type YSOs and solar system meteorites. Further, we are exploring short-term variability in massive YSOs, which requires precise values in column densities and temperatures. This project will enable us to obtain a statistically relevant sample to explore variability in CO reservoirs and isotopic heterogeneity that is applicable to models of the solar nebula. A continuum S/N of 200 in the M-band is needed to detect weaker lines, and for the K-band [for optically thin 12CO], a S/N=100 is desired. We request a total of 14.5 hours of observing time with iSHELL. PROGRAM_ABSTRACT_END