A High Resolution View of Three Massive Young Stellar Objects in the Magellanic Clouds

Abstract

The Magellanic Clouds provide an excellent laboratory to study massive star formation beyond typical Galactic environments. Using ALMA band 7 long-baseline observations, we present the highest resolution (approximately 0.03", $1500{\rm\:au}$) view to date of three massive young stellar objects (MYSOs) in the Magellanic Clouds, i.e., Lh03 and Lh09 in the LMC, and S07 in the SMC. The 0.87 mm continuum, with a sensitivity of $\sim30\:\mu$Jy beam$^{-1}$, reveals varying levels of fragmentation, from a single compact source (S07), a few (Lh03), to a cluster of compact sources (Lh09). In Lh09, we identified 17 core candidates with lowest measured mass of 2.6 Msun, and their de-projected separations peak around 6000~au. All three targets exhibit high velocity CO(3--2) outflows, including detection of a collimated bipolar jet driven by a core in Lh09. Spectral lines from HCO$^+$, SO, and SO$_2$ are detected in all sources. We observe velocity gradients that likely trace rotating toroids (Lh03) or more complex motions (Lh09, S07). Taken together, these phenomena observed on $\sim1500$~au scales are qualitatively similar to those seen in Galactic MYSOs, suggesting a degree of universality in the basic processes of massive star formation across different environments. Nevertheless, the substantial source-to-source diversity in continuum morphology and dense-gas kinematics motivates larger high-resolution surveys to determine how these properties vary with source characteristics and environment.