# # Program information file # PROGRAM_ID 2021A090 PROGRAM_TITLE The Missing Link: Hunting for Phosphene in Hot Molecular Cores 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 Phosphorous is an essential element to life on Earth, but its cosmic abundance is below that of other biogenic molecules. There have been few detections of P-bearing molecules to date in the interstellar medium [ISM]. In particular phosphine [PH3] has attracted attention due its detection in the cloud decks of Venus in abundances higher than can be explained by known chemical and geological processes. On Earth, phosphine is a product of life, and there is an exciting possibility this may be the case for Venus as well. In the cold molecular clouds of the ISM, PH3 is predicted to be the dominant P-bearing molecule frozen onto dust grains. During star-formation, a young protostar heats these dust grains to release gas-phase molecules into the ISM, creating a hot molecular core. So far, the only P-bearing molecules detected towards star-forming regions are PN and PO. PH3 has only one definitive detection in the ISM, in the circumstellar envelope of an evolved star. All these observations were conducted in sub-millimetre, and we are unaware of any MIR detections of P-bearing molecules in the ISM. We propose to search for PH3 with TEXES towards four hot cores known for their molecular richness: AFGL 2591, Mon R2, Orion IRc2, and NGC 7538 IRS 1. PH3 has several strong transitions in the MIR available from the ground. TEXES is one of only two instruments available with the spectral resolution to distinguish individual transitions. We target the strongest transitions that are separate from atmospheric absorption and fall to either side of the deep silicate feature that dims our hot cores. If successful, we will measure the kinematics, temperatures, and abundances of PH3. This gas is the missing link between frozen phosphorus in pre-stellar clouds, and life on Earth. PROGRAM_ABSTRACT_END