Volume 564, April 2014
|Number of page(s)||13|
|Published online||01 April 2014|
1 LERMA, UMR 8112 du CNRS, Observatoire de Paris, 92195 Meudon, France
2 Department of Astronomy, University of Virginia , PO Box 400325, Charlottesville VA 22904, USA
3 Max-Planck-Institut fur Radioastronomie, 53121 Bonn, Germany
4 Université de Cergy-Pontoise, 95031 Cergy Cedex, France
5 The Johns Hopkins University, Department of Physics and Astronomy, 366 Bloomberg Center, 3400 N. Charles Street, Baltimore MD 21218, USA
6 Space Science Institute, 4750 Walnut St. Suite 205, Boulder CO 80301, USA
Received: 18 November 2011
Accepted: 6 February 2014
Context. High-excitation compact H ii regions of the Magellanic Clouds are sites of recent massive star formation in low metallicity environments.
Aims. Detailed study of these regions and their environments using high-spatial resolution observations is necessary to better understand massive star formation, which is still an unsolved problem. We aim at a detailed study of the Small Magellanic Cloud compact H ii region N26, which is only ~4′′ in diameter.
Methods. This study is based on high spatial resolution imaging (~0.̋1–0.̋3) in JHKs and L′ bands, using the VLT equipped with the NAOS adaptive optics system. A larger region (~50 pc × 76 pc) was also imaged at medium spatial resolution, using the ESO 2.2 m telescope in optical wavelengths. We also used the JHKs archival data from the IRSF survey and the Spitzer Space Telescope SAGE-SMC survey.
Results. Our high-resolution JHKs data of the compact high-excitation H ii region N26 reveal a new, bright component (C) between the two already known optical components A and B. Components A and C are resolved into several stars. Component A is the main ionization source of N26 and coincides with the radio continuum source B0046-7333. A new compact H ii region with very faint [O iii] λ5007 emission has been discovered. In the mid-infrared, our field resembles a shell formed by filaments and dust clumps, coinciding with the molecular cloud SMCB2. Region N22, located in the center of the shell, is the most excited H ii region of the complex and seems to have created a cavity in SMCB2. We derive nebular parameters from spectra, and using color–magnitude and color–color diagrams, we identify stellar sources that show significant near-infrared excess emission in order to identify the best YSO candidates.
Key words: Magellanic Clouds / ISM: individual objects: N26 / HII regions / dust, extinction / stars: formation / stars: massive
Full Table 2 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (184.108.40.206) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/564/A31
© ESO, 2014
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