Abstract

The molecules with Si-C bonds (SiCSi,SiC2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\text {SiCSi}, \text {SiC}_2$$\end{document}, and SiC) are thought to play a critical role in the formation of SiC dust around carbon-rich stars. Precise collision rate coefficients for rotational transitions in disilicon carbide due to collisions with para-H2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\text {H}_2$$\end{document} (j=0\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$j=0$$\end{document}) are now available. Thus, this work focuses on the study of the MASER and dasar lines of disilicon carbide using accurate collisional rate coefficients. For available collision rate coefficients for 31 levels, we have considered kinetic temperatures up to 30 K. The molecule SiCSI is an asymmetric b-type with only para levels due to the zero nuclear spin of both the carbon and silicon atoms of the carbon and silicon atoms. We solved a set of 31 statistical equilibrium equations coupled with 62 radiative transfer equations (Sobolev analysis) using accurate collision rate coefficients. Two of 62 radiative transitions exhibited MASER action, while five were identified as dasar lines. The results are compared with those obtained using scaled collision rate coefficients. Significant differences are found, highlighting the importance of using accurate collision coefficients.