2023/05/08 by N. C. Martinez, Martinez, N. C., S. Parón +1
Chemistry · Physics and Astronomy · #Advanced Chemical Physics Studies #Astrophysics and Star Formation Studies #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Molecular Spectroscopy and Structure
paper · pdf · doi:10.48550/arxiv.2305.05073
openalex publication_date 2023/05/08 · openalex created_date 2023/05/12 · openalex updated_date 2026/08/01
The study of molecules and their chemistry in star-forming regions is fundamental to understand the physical process occurring in such regions. The HCN and HNC J=1-0 emissions were used to derive their integrated line intensities (I), to probe a relation recently appeared in the literature between the kinetic temperatures (TK) and the isomeric (I) ratio, and to obtain the isomers abundances (X) in 55 high-mass star-forming regions. These last ones are classified, according to the evolutive stage, as infrared dark clouds, high-mass protostellar objects, hot molecular cores, and ultracompact HII regions. It is inferred that the TK obtained from the isomeric integrated intensity ratio (IHCN/HNC) are underestimated, and hence we suggest that this relation cannot be employed as an universal thermometer in the interstellar medium. The isomers abundances show a behavior that can be explained from the chemistry occurring as the temperature and the UV radiation increase according to the evolutive stage. We found that the abundance ratio (XHCN/HNC) hardly could be used as a chemical clock, and we suggest that it can be approximated by IHCN/HNC. This work is part of an on-going study of multiple molecules that stand in the sample of analyzed regions which intends to contribute in the chemical knowledge of high-mass star formation.