Deep GeMS/GSAOI near-infrared observations of N159W in the Large Magellanic Cloud

¹ Aix-Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 13388 Marseille, France
e-mail: anais.bernard@lam.fr
² ONERA (Office National d’Études et de Recherches Aérospatiales), BP 72, 92322 Chatillon, France
³ Gemini Observatory, c/o AURA, Casilla 603, La Serena, Chile
⁴ UK ATC, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ, UK
⁵ Laboratorio de Astrofísica Teórica e Observacional, Universidade Estadual de Santa Cruz, Rodovia Jorge Amado km16 45662-900 Ilhéus BA, Brazil

Received: 20 April 2016
Accepted: 25 May 2016

Abstract

Aims. The formation and properties of star clusters at the edge of H II 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 JHK_s-band images obtained with the GeMS/GSAOI instrument on the Gemini South telescope. The typical angular resolution of the images is ~100 mas, with a limiting magnitude of H ~ 22 mag (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 H II region and use this to estimate its initial mass function (IMF).

Results. We estimate an age of 2 ± 1 Myr 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 ~1300 M_⊙. We also identify 104 candidate YSOs, which are concentrated in clumps and subclusters of stars, principally at the edges of the H II region. These clusters display signs of recent and active star-formation such as ultra-compact H II 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 H II bubble.