2016A&A...592A..77B

Aims. The formation and properties of star clusters at the edge of HII regions are poorly known, partly due to limitations in angular resolution and sensitivity, which become particularly critical when dealing with extragalactic clusters. In this paper we study the stellar content and star-formation processes in the young N159W region in the Large Magellanic Cloud.
Methods. We investigate the star-forming sites in N159W at unprecedented spatial resolution using JHKs-band images obtained with the GeMS/GSAOI instrument on the Gemini South telescope. The typical angular resolution of the images is ∼100mas, with a limiting magnitude of H∼22mag (90% completeness). Photometry from our images is used to identify candidate young stellar objects (YSOs) in N159W. We also determine the H-band luminosity function of the star cluster at the centre of the HII region and use this to estimate its initial mass function (IMF).
Results. We estimate an age of 2±1Myr for the central cluster, with its IMF described by a power-law with an index of Γ=-1.05±0.2, and with a total estimated mass of ∼1300M_☉. We also identify 104 candidate YSOs, which are concentrated in clumps and subclusters of stars, principally at the edges of the HII region. These clusters display signs of recent and active star-formation such as ultra-compact HII regions, and molecular outflows. This suggests that the YSOs are typically younger than the central cluster, pointing to sequential star-formation in N159W, which has probably been influenced by interactions with the expanding HII bubble.