Volume 515, June 2010
|Number of page(s)||13|
|Section||Catalogs and data|
|Published online||09 June 2010|
Recent star formation at low metallicities. The star-forming region NGC 346/N66 in the Small Magellanic Cloud from near-infrared VLT/ISAAC observations *,**
Max-Planck-Institut für Astronomie, Königstuhl 17,
69117 Heidelberg, Germany e-mail: email@example.com
2 Armagh Observatory, College Hill, Armagh BT61 9DG, UK
Accepted: 27 February 2010
Context. The emission nebula N66 is the brightest H II region in the Small Magellanic Cloud (SMC), the stellar association NGC 346 being located at its center. The youthfulness of the region NGC 346/N66 is well documented by studies of the gas and dust emission, and the detection in the optical of a rich sample of pre-main sequence (PMS) stars, and in the mid- and far-IR of young stellar objects (YSOs). However, a comprehensive study of this region has not been performed in the near-IR that would bridge the gap between previous surveys.
Aims. We perform a photometric analysis on deep, seeing-limited near-IR VLT images of the region NGC 346/N66 and a nearby control field of the SMC to locate the centers of active high- and intermediate-mass star formation by identifying near-IR bright objects as candidate stellar sources under formation.
Methods. We use archival imaging data obtained with the high-resolution camera ISAAC at VLT of NGC 346/N66 to construct the near-IR color–magnitude (CMD) and color–color diagrams (C-CD) of all detected sources. We investigate the nature of all stellar populations in the observed CMDs, and we identify all stellar sources that show significant near-IR excess emission in the observed C-CD. We, thus, select the most likely young stellar sources.
Results. Based on their near-IR colors, we select 263 candidate young stellar sources. This sample comprises a variety of objects, such as intermediate-mass PMS and Herbig Ae/Be stars and possible massive YSOs, providing original near-IR colors for each of them. The spatial distribution of the selected candidate sources indicates that they are located along the dusty filamentary structures of N66 seen in mid- and far-IR dust emission and agrees very well with that of previously detected candidate YSOs and PMS stars.
Conclusions. Our study provides an original accurate set of near-IR colors for candidate young stellar sources. This provides significant information about the star formation process in NGC 346/N66, but does not establish the types of these objects, which requires the construction of complete spectral energy distributions for individual sources from multiwavelength data. This would be an important follow-up study to that presented here.
Key words: stars: pre-main-sequence / Magellanic Clouds / open clusters and associations: individual: NGC 346 / HII regions / ISM: individual objects: LHA 115-N66 / catalogs
Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under program ID 063.I-0329.
Table 1 is available in its entirety only in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/515/A56
© ESO, 2010
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.