Speaker
Description
Despite a rather low elemental abundance of $\sim 3\times 10^{-7}$ (Asplund et al. 2009), Phosphorus is one of the main biogenic elements, present in all life forms on Earth. As such, phosphorus-bearing compounds, in particular their P--O bonds, play a key role in many biochemical and metabolic processes in living systems. However, Phosphorus chemistry in the interstellar medium has received relatively little attention until now and remains poorly known.
We present here the results of a systematic search for P-bearing molecules in solar-type star forming regions, in the course of the Large Program "Astrochemical Surveys At IRAM" (ASAI; Lefloch et al. 2018) with the IRAM 30m telescope. The sample comprised 10 objects illustrative of the different chemical stages of evolution of a sun-like protostar, from the early prestellar to the late protostellar (Class I) phase, and two protostellar shock regions.
Transitions of the simple PN and PO molecules were detected towards a subsample of protostars and a protostellar shock region. Physical conditions and molecular abundances were obtained for both species. We will discuss the results of our study, in particular the shock region, which was subsequently observed at high-angular resolution (2'') with the NOEMA interferometer. Our results imply a strong P depletion ($\approx 100$) in the quiescent cloud gas.
A simple modelling using the UCL_CHEM code coupled with a parametric C-shock model has allowed us to bring constraints on phosphorus chemistry and shows the important role played by atomic N in the formation and destruction routes of PO and PN.
