Identification of Methyl Isocyanate and Other Complex Organic Molecules in a Hot Molecular Core, G31.41+0.31

TL;DR

This study uses ALMA observations to identify methyl isocyanate and other complex organic molecules in the hot molecular core G31.41+0.31, revealing insights into their formation and physical conditions in star-forming regions.

Contribution

First detection of methyl isocyanate in G31.41+0.31 and analysis of complex organic molecules' physical properties in this hot core.

Findings

Methyl isocyanate and other COMs are detected in G31.41+0.31.

COMs are likely formed on grain/ice phases and released into the gas phase.

Multiple temperature components are present in the hot core environment.

Abstract

G31.41+0.31 is a well known chemically rich hot molecular core (HMC). Using Band 3 observations of Atacama Large Millimeter Array (ALMA), we have analyzed the chemical and physical properties of the source. We have identified methyl isocyanate (CH3NCO), a precursor of prebiotic molecules, towards the source. In addition to this, we have reported complex organic molecules (COMs) like methanol (CH3OH), methanethiol (CH3SH), and methyl formate (CH3OCHO). Additionally, we have used transitions from molecules like HCN, HCO+, SiO to trace the presence of infall and outflow signatures around the star-forming region. For the COMs, we have estimated the column densities and kinetic temperatures, assuming molecular excitation under local thermodynamic equilibrium (LTE) conditions. From the estimated kinetic temperatures of certain COMs, we found that multiple temperature components may be present in the HMC environment. Comparing the obtained molecular column densities between the existing observational results toward other HMCs, it seems that the COMs are favourably produced in the hot-core environment ($\sim 100$ K or higher). Though the spectral emissions towards G31.41+0.31 are not fully resolved, we find that CH$_3$NCO and other COMs are possibly formed on the grain/ice phase and populate the gas environment similar to other hot cores like Sgr B2, Orion KL, and G10.47+0.03, etc.