A study of warm molecular gas traced by 12CO(3–2) and 13CO(3–2) emission in the N44 molecular cloud using the Atacama Submillimeter Telescope Experiment

We explore the properties of massive molecular clumps in the N44 star-forming region of the Large Magellanic Cloud (LMC) using observations of ¹²CO(3–2) and ¹³CO(3–2) emission by the Atacama Submillimeter Telescope Experiment (ASTE), and ¹³CO(1–0) from the Atacama Large Millimeter/submillimeter Array (ALMA). The distribution of ¹²CO and ¹³CO emission in the N44 CD cloud reveals a complex, clumpy filamentary structure. We determine that the total H₂ mass of the N44 CD clump is ~ 3.2× 10⁴ M with a radius of ~7.24 pc located between two H ii regions (N44 C and N44 D). The accumulation of young stellar objects (YSOs) is significant near the peak of CO emission in the N44 CD molecular clump. The internal features within this massive clump are revealed in the ALMA ¹³CO(1–0) observation. These clumps show filamentary and bar-like structures. With the help of Magellanic Mopra Assessment (MAGMA) data, we see that the densest part of this clump shows a very high value of ¹²CO(3–2)/¹²CO(1–0) ~ 3.2± 0.32 compared with other clouds in the LMC. The time difference between the dynamical age of the H ii regions and the age of nearby YSOs hints that stellar feedback may influence the conditions for forming a new generation of stars. It suggests that the expansion of the H ii regions could contribute to material compression in surrounding areas. We detect another separate clump associated with the N44 A H ii region at the north-east side of the N44 region, which was marginally detected by MAGMA. Therefore, the observation of high-excitation CO lines demonstrates the capability of detecting compact clouds influenced by feedback from the H ii regions.