# Internal Structures of Molecular Clouds in the LMC Revealed by ALMA

## TL;DR

This study uses high-resolution ALMA observations to analyze the internal structures of five GMCs in the LMC, revealing differences related to star formation activity and suggesting an evolutionary sequence.

## Contribution

It provides detailed structural analysis of GMCs in the LMC using ALMA, highlighting differences between star-forming and quiescent clouds and proposing an evolutionary trend.

## Key findings

- Star-forming GMCs have complex clumpy and filamentary structures.
- Quiescent GMCs show diffuse, unstructured emission.
- An evolutionary trend from less to more structured GMCs is suggested.

## Abstract

We observed five giant molecular clouds (GMCs) in the Large Magellanic Cloud (LMC) in the 12CO J=1-0 line using the Atacama Large Millimeter/submillimeter Array (ALMA). The sample includes four GMCs with some signs of star formation -- either YSOs, H II regions, and/or young clusters -- and one quiescent GMC without any sign of massive star formation. The data from the ALMA 12 m, 7 m, and Total-Power arrays are jointly deconvolved to obtain high-fidelity images at high spatial resolution (3 arcsec = 0.7 pc). The four star-forming GMCs show very complex structures with clumps and filaments. The quiescent GMC shows a relatively diffuse, extended emission distribution without prominent clumps or filaments. This difference is similar to that between structured molecular gas in Milky Way spiral arms and unstructured gas in the inter-arm regions. We characterize the difference with the brightness distribution function and brightness distribution index. In conjunction with other ALMA studies of GMCs in the LMC, the five GMCs tentatively form an evolutionary trend: from less structured, quiescent GMCs to more structured, actively star-forming GMCs. A future ALMA study will be able to map molecular clouds over the LMC and reveal the evolutionary sequence of molecular clouds.