# # Program information file # PROGRAM_ID 2024A067 PROGRAM_TITLE High-resolution MIR Spectroscopy of W33A: Molecular signatures of Outflow walls versus Disks PROGRAM_INV1 Curtis DeWitt PROGRAM_INV2 John Lacy PROGRAM_INV3 Adwin Boogert PROGRAM_INV4 Matthew Richter PROGRAM_INV5 PROGRAM_SCICAT galactic/interstellar medium PROGRAM_ABSTRACT_BEG High resolution mid-IR molecular line studies make 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 of C2H2 and HCN in the N-band and compare the properties of the absorption to other HMYSOs said to be dominated by MIR bright disks. This will lead to a new understanding of which chemical, thermal and kinematic signatures can be used to diagnose HMYSO source structure. PROGRAM_ABSTRACT_END