The NH2D/NH3 ratio toward pre-protostellar cores around the UCHII region in IRAS 20293+3952

TL;DR

This study measures the deuterium fractionation ratio (Dfrac) in pre-protostellar cores around the UCHII region IRAS 20293+3952, revealing high Dfrac values that may indicate core evolution, using high-resolution IRAM and VLA observations.

Contribution

It provides high angular resolution measurements of Dfrac in a cluster environment near an UCHII region, linking deuterium fractionation to core evolution in high-mass star-forming regions.

Findings

High Dfrac values (~0.1-0.8) in pre-protostellar cores.

Low Dfrac (<0.1) associated with young stellar objects.

Deuterium fractionation may indicate core evolutionary stage.

Abstract

The deuterium fractionation, Dfrac, has been proposed as an evolutionary indicator in pre-protostellar and protostellar cores of low-mass star-forming regions. We investigate Dfrac, with high angular resolution, in the cluster environment surrounding the UCHII region IRAS 20293+3952. We performed high angular resolution observations with the IRAM Plateau de Bure Interferometer (PdBI) of the ortho-NH2D 1_{11}-1_{01} line at 85.926 GHz and compared them with previously reported VLA NH3 data. We detected strong NH2D emission toward the pre-protostellar cores identified in NH3 and dust emission, all located in the vicinity of the UCHII region IRAS 20293+3952. We found high values of Dfrac~0.1-0.8 in all the pre-protostellar cores and low values, Dfrac<0.1, associated with young stellar objects. The high values of Dfrac in pre-protostellar cores could be indicative of evolution, although outflow interactions and UV radiation could also play a role.