IRTF Data Archive Program Information

# # Program information file # PROGRAM_ID 2021A082 PROGRAM_TITLE Excavating the Molecular Secrets of Massive Star Formation in W51A PROGRAM_INV1 Sarah Nickerson PROGRAM_INV2 Naseem Rangwala PROGRAM_INV3 John Lacy PROGRAM_INV4 Sean Colgan PROGRAM_INV5 Curtis DeWitt PROGRAM_SCICAT galactic/interstellar medium PROGRAM_ABSTRACT_BEG Compared to the formation of low-mass stars, massive star formation remains poorly understood. Massive stars live briefly, spending their earliest evolutionary stages in the dusty, molecular gas that birthed them. It is during this stage that they are obscured to most wavelengths but are bright in the mid-infrared [MIR]. The MIR is challenged by low spectral resolution in space-based missions [e.g. ISO, Spitzer, and JWST]. TEXES is one of only two instruments that can access the MIR with enough spectral resolution to distinguish individual transitions and identify molecules with certainty. SOFIA/FORCAST has recently imaged W51A, the site of an unprecedented burst of clustered massive star formation. They have identified 41 sources as massive young stellar object [MYSO] candidates, many for the first time. We propose follow-up TEXES observations on three of the brightest MYSOs, two of which were newly discovered. These sources represent diverse spectral types and masses. We will target C2H2, HCN, and NH3, three key molecules observable from the ground. Previous unpublished TEXES observations of our brightest target, IRS2E, has revealed C2H2 and HCN, while the other two targets are newly discovered. We choose the TEXES hi-med mode for superior performance and propose select settings with the strongest molecular transitions that are separate fro atmospheric lines, considering the targets' Doppler shifts. Our fluxes for integration time calculations take into account TEXES's small beam size. Analysis of these molecules' spectral lines will elucidate the physical conditions, kinematics, chemical abundances, and relative ages of the molecular gas enveloping these MYSOs. This is an important opportunity to study a poorly understood process, massive star formation, at an under-utilized wavelength, the MIR, and will yield results of great interest to both the star-formation and astrochemistry communities. PROGRAM_ABSTRACT_END