Hostname: page-component-cd9895bd7-8ctnn Total loading time: 0 Render date: 2024-12-22T13:54:30.525Z Has data issue: false hasContentIssue false

Cluster Assembly in Hierarchically Collapsing Clouds

Published online by Cambridge University Press:  31 March 2017

Enrique Vázquez-Semadeni
Affiliation:
Instituto de Radioastronomía y Astrofísica, UNAM Antigua Carretera a Pátzcuaro # 8701, Morelia, Michoacán, 58088, México email: e.vazquez@crya.unam.mx, m.zamora@crya.unam.mx, p.colin@crya.unam.mx
Alejandro González-Samaniego
Affiliation:
Instituto de Astronomía, UNAM, Circuito Exterior, S/N, México, D.F., 04510, México email: ags@astro.unam.mx
Manuel Zamora-Avilés
Affiliation:
Instituto de Radioastronomía y Astrofísica, UNAM Antigua Carretera a Pátzcuaro # 8701, Morelia, Michoacán, 58088, México email: e.vazquez@crya.unam.mx, m.zamora@crya.unam.mx, p.colin@crya.unam.mx
Pedro Colín
Affiliation:
Instituto de Radioastronomía y Astrofísica, UNAM Antigua Carretera a Pátzcuaro # 8701, Morelia, Michoacán, 58088, México email: e.vazquez@crya.unam.mx, m.zamora@crya.unam.mx, p.colin@crya.unam.mx
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

We discuss the mechanism of cluster formation in hierarchically collapsing molecular clouds. Recent evidence, both observational and numerical, suggests that molecular clouds (MCs) may be undergoing global, hierarchical gravitational collapse. The “hierarchical” regime consists of small-scale collapses within larger-scale ones. The latter implies that the star formation rate increases systematically during the early stages of evolution, and occurs via filamentary flows onto “hubs” of higher density, mass, and velocity dispersion, and culminates a few Myr after than the small-scale collapses have started to form stars. In turn, the small-scale collapses occur in clumps embedded in the filaments, and are themselves falling into the larger potential well of the still-ongoing large-scale collapse. The stars formed in the early, small-scale collapses share the infall motion of their parent clumps towards the larger potential trough, so that the filaments feed both gaseous and stellar material to the hubs. This leads to the presence of older stars in a region where new protostars are still forming, to a scale-free or fractal structure of the clusters, in which each unit is composed of smaller-scale ones, and to the eventual merging of the subunits, explaining the observed structural features of open clusters.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2017 

References

Bertoldi, F. & McKee, C. F. 1992, ApJ, 395, 140 Google Scholar
Bressert, E., Bastian, N., Gutermuth, R., et al. 2010, MNRAS, 409, L54 Google Scholar
Colín, P., Vázquez-Semadeni, E., & Gómez, G. C. 2013, MNRAS, 435, 1701 CrossRefGoogle Scholar
Federrath, C. & Klessen, R. S. 2012, ApJ, 761, 156 Google Scholar
Franco, J., Shore, S. N., & Tenorio-Tagle, G. 1994, ApJ, 436, 795 Google Scholar
Gao, Y. & Solomon, P. M. 2004, ApJ, 606, 271 CrossRefGoogle Scholar
Gómez, G. C. & Vázquez-Semadeni, E. 2014, ApJ, 791, 124 Google Scholar
Hartmann, L., Ballesteros-Paredes, J., & Heitsch, F. 2012, MNRAS, 420, 1457 Google Scholar
Heitsch, F., Burkert, A., Hartmann, L. W., Slyz, A. D., & Devriendt, J. E. G. 2005, ApJL, 633, L113 Google Scholar
Hennebelle, P. & Chabrier, G. 2011, ApJL, 743, L29 Google Scholar
Hillenbrand, L. A. & Hartmann, L. W. 1998, ApJ, 492, 540 Google Scholar
Hoyle, F. 1953, ApJ, 118, 513 Google Scholar
Kim, J. & Ryu, D. 2005, ApJL, 630, L45 Google Scholar
Kirk, H., Offner, S. S. R., & Redmond, K. J. 2014, MNRAS, 439, 1765 Google Scholar
Koyama, H. & Inutsuka, S.-i. 2002, ApJL, 564, L97 CrossRefGoogle Scholar
Kravtsov, A. V., Klypin, A. A., & Khokhlov, A. M. 1997, ApJS, 111, 73 Google Scholar
Krumholz, M. R. & McKee, C. F. 2005, ApJ, 630, 250 CrossRefGoogle Scholar
Kuhn, M. A., Getman, K. V., & Feigelson, E. D. 2015a, ApJ, 802, 60 Google Scholar
Kuhn, M. A., Feigelson, E. D., Getman, K. V., et al. 2015b, arXiv:1507.05653Google Scholar
Lada, C. J. & Lada, E. A. 2003, ARA&A, 41, 57 Google Scholar
Palla, F. & Stahler, S. W. 2000, ApJ, 540, 255 Google Scholar
Rivera-Gálvez, S., Román-Zúñiga, C. G., Jiménez-Bailón, E., et al. 2015, arXiv:1510.02835Google Scholar
Vázquez-Semadeni, E. 1994, ApJ, 423, 681 Google Scholar
Vázquez-Semadeni, E., Gómez, G. C., Jappsen, A.-K., Ballesteros-Paredes, J., & Klessen, R. S. 2009, ApJ, 707, 1023 CrossRefGoogle Scholar
Vishniac, E. T. 1994, ApJ, 428, 186 Google Scholar
Williams, J. P. & McKee, C. F. 1997, ApJ, 476, 166 Google Scholar
Zamora-Avilés, M., Vázquez-Semadeni, E., & Colín, P. 2012, ApJ, 751, 77 Google Scholar
Zamora-Avilés, M. & Vázquez-Semadeni, E. 2014, ApJ, 793, 84 Google Scholar