# # Program information file # PROGRAM_ID 2023B087 PROGRAM_TITLE High-resolution MIR Spectroscopy of W33A: Molecular signatures of Outflow walls versus Disks PROGRAM_INV1 Curtis DeWitt PROGRAM_INV2 Matthew Richter PROGRAM_INV3 John Lacy PROGRAM_INV4 PROGRAM_INV5 PROGRAM_SCICAT galactic/interstellar medium PROGRAM_ABSTRACT_BEG High resolution mid-IR molecular line studies have the promise of locating gas in high-mass YSO systems but rarely deliver this message with total clarity. The uncertainty arises because we lack sufficient spatial resolution of these systems and because the infrared radiation may be dominated by disks, envelopes or cavities walls depending on evolutionary phase, orientation or a host of other factors. W33A is a famous massive protostar that has been studied intensely in the mid-infared with space based missions and with high-angular resolution N-band [8-13um] interferometry with VLTI. These studies conclude that the mid-IR continuum is dominated by outflow cavity walls, and that the accretion disk around the protostar has little contribution. We will therefore target this protostar with TEXES high-resolution spectroscopy to characterize the molecular absorption signatures of absorption lines against warm cavity walls. We will compare these signatures to absorption seen toward HMYSOs like AFGL 2136 which has been claimed to arise within an accretion disk. PROGRAM_ABSTRACT_END