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NGC 346: Looking in the Cradle of a Massive Star Cluster

Published online by Cambridge University Press:  31 March 2017

Dimitrios A. Gouliermis  and
Sacha Hony
Dimitrios A. Gouliermis
Affiliation:
University of Heidelberg, Centre for Astronomy, Institute for Theoretical Astrophysics, Albert-Ueberle-Str. 2, 69120 Heidelberg, Germany email: [email protected], [email protected]
Sacha Hony
Affiliation:
University of Heidelberg, Centre for Astronomy, Institute for Theoretical Astrophysics, Albert-Ueberle-Str. 2, 69120 Heidelberg, Germany email: [email protected], [email protected]
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Abstract

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How does a star cluster of more than few 10,000 solar masses form? We present the case of the cluster NGC 346 in the Small Magellanic Cloud, still embedded in its natal star-forming region N66, and we propose a scenario for its formation, based on observations of the rich stellar populations in the region. Young massive clusters host a high fraction of early-type stars, indicating an extremely high star formation efficiency. The Milky Way galaxy hosts several young massive clusters that fill the gap between young low-mass open clusters and old massive globular clusters. Only a handful, though, are young enough to study their formation. Moreover, the investigation of their gaseous natal environments suffers from contamination by the Galactic disk. Young massive clusters are very abundant in distant starburst and interacting galaxies, but the distance of their hosting galaxies do not also allow a detailed analysis of their formation. The Magellanic Clouds, on the other hand, host young massive clusters in a wide range of ages with the youngest being still embedded in their giant HII regions. Hubble Space Telescope imaging of such star-forming complexes provide a stellar sampling with a high dynamic range in stellar masses, allowing the detailed study of star formation at scales typical for molecular clouds. Our cluster analysis on the distribution of newly-born stars in N66 shows that star formation in the region proceeds in a clumpy hierarchical fashion, leading to the formation of both a dominant young massive cluster, hosting about half of the observed pre–main-sequence population, and a self-similar dispersed distribution of the remaining stars. We investigate the correlation between stellar surface density (and star formation rate derived from star-counts) and molecular gas surface density (derived from dust column density) in order to unravel the physical conditions that gave birth to NGC 346. A power law fit to the data yields a steep correlation between these two parameters with a considerable scatter. The fraction of stellar over the total (gas plus young stars) mass is found to be systematically higher within the central 15 pc (where the young massive cluster is located) than outside, which suggests variations in the star formation efficiency within the same star-forming complex. This trend possibly reflects a change of star formation efficiency in N66 between clustered and non-clustered star formation. Our findings suggest that the formation of NGC 346 is the combined result of star formation regulated by turbulence and of early dynamical evolution induced by the gravitational potential of the dense interstellar medium.

Keywords

stars: pre-main-sequencestars: statisticsH II regionsISM: structureISM: individual: LHA 115-N66open clusters and associations: individual: NGC 346Magellanic Clouds
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 12 , Symposium S316: Formation, evolution, and survival of massive star clusters , August 2015 , pp. 117 - 122
Copyright
Copyright © International Astronomical Union 2017 

References

Elmegreen, B. G., 2011, in: Charbonnel, C. & Montmerle, T. (eds.), Star Formation in the Local Universe, EAS Publications Series Vol. 51 (Cambridge: Cambridge Univ. Press), p. 31 Google Scholar
Elson, R. A. W., Fall, S. M., & Freeman, K. C. 1987, ApJ, 323, 54 Google Scholar
Federrath, C., Klessen, R. S., & Schmidt, W. 2009, ApJ, 692, 364 Google Scholar
Girichidis, P., Federrath, C., Allison, R., et al. 2012, MNRAS, 420, 3264 Google Scholar
Goodwin, S. P. & Whitworth, A. P. 2004, A&A, 413, 929 Google Scholar
Gordon, K. D., Meixner, M., Meade, M. R., et al. 2011, AJ, 142, 102 Google Scholar
Gouliermis, D. A. 2012, Space Sci. Revs, 169, 1 Google Scholar
Gouliermis, D. A., Dolphin, A. E., Brandner, W., Henning, T., 2006, ApJS, 166, 549 Google Scholar
Gouliermis, D. A., Schmeja, S., Klessen, R. S., et al. 2010, ApJ, 725, 1717 Google Scholar
Gouliermis, D. A., Hony, S., & Klessen, R. S. 2014, MNRAS, 439, 3775 Google Scholar
Gouliermis, D. A., Thilker, D., Elmegreen, B. G., et al. 2015, MNRAS, 452, 3508 Google Scholar
Heiderman, A., Evans, N. J. II, Allen, L. E., Huard, T., & Heyer, M. 2010, ApJ, 723, 1019 Google Scholar
Hony, S., Galliano, F., Madden, S. C., et al. 2010, A&A, 518, L76 Google Scholar
Hony, S., Gouliermis, D. A., Galliano, F., et al. 2015, MNRAS, 448, 1847 Google Scholar
Kennicutt, R. C. & Evans, N. J. 2012, ARAA, 50, 531 Google Scholar
Lada, C. J. & Lada, E. A. 2003, ARAA, 41, 57 Google Scholar
Meixner, M., Panuzzo, P., Roman-Duval, J., et al. 2013, AJ, 146, 62 Google Scholar
Mokiem, M. R., de Koter, A., Evans, C. J., et al. 2006, A&A, 456, 1131 Google Scholar
Parker, R. J., Wright, N. J., Goodwin, S. P., & Meyer, M. R. 2014, MNRAS, 438, 620 Google Scholar
Peebles, P. J. E. 1980, The large-scale structure of the universe (Princeton Univ. Press)Google Scholar
Portegies Zwart, S. F., McMillan, S. L. W., & Gieles, M. 2010, ARAA, 48, 431 Google Scholar
Sabbi, E., Sirianni, M., Nota, A., et al. 2008, AJ, 135, 173 Google Scholar
Schmeja, S., Gouliermis, D. A., & Klessen, R. S. 2009, ApJ, 694, 367 Google Scholar