ALMA Observations of Molecular Complexity in the Large Magellanic Cloud: Probing the Star-forming Region N160

TL;DR

This study uses ALMA to observe molecular complexity in the star-forming region N160 of the Large Magellanic Cloud, identifying a new extragalactic hot core with rich organic molecules, advancing understanding of star formation in different environments.

Contribution

First detection of a hot core with complex organic molecules in the LMC using ALMA, revealing chemical richness and physical properties in an extragalactic environment.

Findings

Identified a chemically rich hot core, N160A-mmA, with temperatures exceeding 100 K.

Detected multiple complex organic molecules, including methanol and methyl cyanide.

Compared molecular abundances with Galactic hot cores, highlighting environmental differences.

Abstract

Hot cores are small ($\lesssim$0.1 pc), dense ($\geq$10$^6$ cm$^{-3}$), and hot ($>$100 K) regions around massive protostars and are one of the main production sites of complex organic molecules (COMs, $\geq6$ atoms, including carbon). The Large Magellanic Cloud (LMC) is an ideal place to study hot core and COM formation in an environment that is different from our Galaxy, though prior to this study there have only been nine detections of extragalactic hot cores (seven in the LMC and two in the Small Magellanic Cloud, SMC). Here, we report 1.2 mm continuum and molecular line observations with the Atacama Large Millimeter/submillimeter Array (ALMA) in the star-forming region N160 that we named N160A-mm. We identify six 1.2 mm continuum sources, four of which are associated with methanol (CH$_3$OH) emission. Another COM, methyl cyanide (CH$_3$CN) is associated with the brightest source, N160A-mmA, the most chemically rich source in the field. Using the XCLASS software, we perform spectral modeling to estimate rotational temperatures and total column densities of detected molecular species for four sources. Based on the temperature exceeding 100 K, small size, and high H$_2$ number density, we identify N160A-mmA as a hot core. We compare the molecular abundances of this newly detected hot core with those previously detected in the LMC and SMC, as well as with a sample of Galactic hot cores, and discuss the complex nature of N160A-mmA.