VLT/NACO near-infrared imaging and spectroscopy of N159A in the LMC HII complex

G. Testor$^{1}$, J.L. Lemaire$^{2}$, D. Field$^{3}$, S. Diana$^{2}$

$^{1}$ LUTH, UMR 8102 du CNRS, Observatoire de Paris, 92195 Meudon, France

$^{2}$ LERMA, UMR 8112 du CNRS, Observatoire de Paris, 92195 Meudon, France
and Universit\'e de Cergy-Pontoise, 95031 Cergy Cedex.

$^{3}$ Department of Physics and Astronomy, \AA{}rhus University, 8000
\AA{}rhus C, Denmark.

We present near-infrared imaging and spectrocopic observations of the
HII region N159A ($\sim$ 10 pc) in the giant star-forming region N159 (50 pc)
in the LMC. N159A was observed in the J and Ks bands at high spatial resolution
$\sim$ 0.2$\arcsec$ using the ESO Very Large Telescope UT4 (VLT), equipped with the
NAOS adaptative optics system. Our data reveal the morphology of this region in
unprecedented detail. The protostar P2, one of the first YSOs of Class I identified
in the LMC is now resolved in two YSO candidates. The ultracompact HII region
LI-LMC 1501W is found to be a tight cluster embedded in a compact HII region ionised
by a late O source. A new multiple system composed of a tight star cluster and
an YSO candidate, all embedded in a compact nebular region (0.4 pc) is also detected
at the north-east edge of N159A. The stellar population of the whole N159A region
appears composed of two main stellar populations, one with an age $\leq$ 3 Myr
and the other one with a large range of age (300 Myr - 10 Gyr). Using spectroscopy,
one of the two exciting O stars in the HII region N159A is classified O5-O6.

Reference: Astronomy and Astrophysics
Status: Manuscript has been accepted

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Email: testor@mesiog.obspm.fr