Year: 2019
Type: article
Abstract: The chemical structure of high-mass star nurseries is important for a general understanding of star formation. Deuteration is a key chemical process in the earliest stages of star formation because its efficiency is sensitive to the environment. Using the IRAM-30 m telescope at 1.3–4.3 mm wavelengths, we have imaged two parsec-scale high-mass protostellar clumps (P1 and S) that show different evolutionary stages but are located in the same giant filamentary infrared dark cloud G28.34+0.06. Deep spectral images at subparsec resolution reveal the dust and gas physical structures of both clumps. We find that (1) the low- J lines of N 2 H + , HCN, HNC, and HCO + isotopologues are subthermally excited; and (2) the deuteration of N 2 H + is more efficient than that of HCO + , HCN, and HNC by an order of magnitude. The deuterations of these species are enriched toward the chemically younger clump S compared with P1, indicating that this process favors the colder and denser environment ( T kin ∼ 14 K, N (NH 3 ) ∼ 9 × 10 15 cm −2 ). In contrast, single deuteration of NH 3 is insensitive to the environmental difference between P1 and S; and (3) single deuteration of CH 3 OH (>10%) is detected toward the location where CO shows a depletion of ∼10. This comparative chemical study between P1 and S links the chemical variations to the environmental differences and shows chemical similarities between the early phases of high- and low-mass star-forming regions.
Source: The Astrophysical Journal
Authors: S. 思轶 Feng 冯, P. Caselli, K. 科 Wang 王, Y. Lin, H. Beuther, O. Sipilä
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Funders: Deutsche Forschungsgemeinschaft, National Natural Science Foundation of China, Academia Sinica, Korea Astronomy and Space Science Institute, National Astronomical Observatory of Japan, Peking University, East Asian Core Observatories Association, National Key Research and Development Program of China
OpenAlex ID: W2971625582