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Title: The Hierarchical Distribution of the Young Stellar Clusters in Six Local Star-forming Galaxies

Abstract

We present a study of the hierarchical clustering of the young stellar clusters in six local (3–15 Mpc) star-forming galaxies using Hubble Space Telescope broadband WFC3/UVIS UV and optical images from the Treasury Program LEGUS (Legacy ExtraGalactic UV Survey). We identified 3685 likely clusters and associations, each visually classified by their morphology, and we use the angular two-point correlation function to study the clustering of these stellar systems. We find that the spatial distribution of the young clusters and associations are clustered with respect to each other, forming large, unbound hierarchical star-forming complexes that are in general very young. The strength of the clustering decreases with increasing age of the star clusters and stellar associations, becoming more homogeneously distributed after ∼40–60 Myr and on scales larger than a few hundred parsecs. In all galaxies, the associations exhibit a global behavior that is distinct and more strongly correlated from compact clusters. Thus, populations of clusters are more evolved than associations in terms of their spatial distribution, traveling significantly from their birth site within a few tens of Myr, whereas associations show evidence of disruption occurring very quickly after their formation. The clustering of the stellar systems resembles that of a turbulentmore » interstellar medium that drives the star formation process, correlating the components in unbound star-forming complexes in a hierarchical manner, dispersing shortly after formation, suggestive of a single, continuous mode of star formation across all galaxies.« less

Authors:
;  [1]; ;  [2];  [3];  [4];  [5];  [6];  [7]; ;  [8];  [9];  [10];  [11];  [12]; ;  [13];  [14];  [15]
  1. Astronomy Department, University of Massachusetts, Amherst, MA 01003 (United States)
  2. Dept. of Astronomy, The Oskar Klein Centre, Stockholm University, Stockholm (Sweden)
  3. Gemini Observatory, La Serena (Chile)
  4. IBM Research Division, T.J. Watson Research Center, Yorktown Hts., NY (United States)
  5. Zentrum für Astronomie der Universität Heidelberg, Institut für Theoretische Astrophysik, Albert-Ueberle-Str. 2, D-69120 Heidelberg (Germany)
  6. Dept. of Physics and Astronomy, University of Wyoming, Laramie, WY (United States)
  7. Institute for Computational Cosmology and Centre for Extragalactic Astronomy, Durham University, Durham (United Kingdom)
  8. Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, Mönchhofstr. 12-14, D-69120 Heidelberg (Germany)
  9. Dept. of Astronomy, University of Virginia, Charlottesville, VA (United States)
  10. Dept. of Astronomy, New Mexico State University, Las Cruces, NM (United States)
  11. Institute of Astronomy, University of Cambridge, Cambridge (United Kingdom)
  12. Dept. of Physics and Astronomy, State University of New York at Geneseo, Geneseo NY (United States)
  13. Space Telescope Science Institute, Baltimore, MD (United States)
  14. European Space Agency/Space Telescope Science Institute, Baltimore, MD (United States)
  15. Dept. of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD (United States)
Publication Date:
OSTI Identifier:
22663605
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 840; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CORRELATION FUNCTIONS; CORRELATIONS; GALAXIES; PARTURITION; SPACE; SPATIAL DISTRIBUTION; STAR CLUSTERS; STARS; TELESCOPES; ULTRAVIOLET RADIATION

Citation Formats

Grasha, K., Calzetti, D., Adamo, A., Messa, M., Kim, H., Elmegreen, B. G., Gouliermis, D. A., Dale, D. A., Fumagalli, M., Grebel, E. K., Shabani, F., Johnson, K. E., Kahre, L., Kennicutt, R. C., Pellerin, A., Ryon, J. E., Ubeda, L., Smith, L. J., and Thilker, D., E-mail: kgrasha@astro.umass.edu. The Hierarchical Distribution of the Young Stellar Clusters in Six Local Star-forming Galaxies. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA6F15.
Grasha, K., Calzetti, D., Adamo, A., Messa, M., Kim, H., Elmegreen, B. G., Gouliermis, D. A., Dale, D. A., Fumagalli, M., Grebel, E. K., Shabani, F., Johnson, K. E., Kahre, L., Kennicutt, R. C., Pellerin, A., Ryon, J. E., Ubeda, L., Smith, L. J., & Thilker, D., E-mail: kgrasha@astro.umass.edu. The Hierarchical Distribution of the Young Stellar Clusters in Six Local Star-forming Galaxies. United States. doi:10.3847/1538-4357/AA6F15.
Grasha, K., Calzetti, D., Adamo, A., Messa, M., Kim, H., Elmegreen, B. G., Gouliermis, D. A., Dale, D. A., Fumagalli, M., Grebel, E. K., Shabani, F., Johnson, K. E., Kahre, L., Kennicutt, R. C., Pellerin, A., Ryon, J. E., Ubeda, L., Smith, L. J., and Thilker, D., E-mail: kgrasha@astro.umass.edu. Wed . "The Hierarchical Distribution of the Young Stellar Clusters in Six Local Star-forming Galaxies". United States. doi:10.3847/1538-4357/AA6F15.
@article{osti_22663605,
title = {The Hierarchical Distribution of the Young Stellar Clusters in Six Local Star-forming Galaxies},
author = {Grasha, K. and Calzetti, D. and Adamo, A. and Messa, M. and Kim, H. and Elmegreen, B. G. and Gouliermis, D. A. and Dale, D. A. and Fumagalli, M. and Grebel, E. K. and Shabani, F. and Johnson, K. E. and Kahre, L. and Kennicutt, R. C. and Pellerin, A. and Ryon, J. E. and Ubeda, L. and Smith, L. J. and Thilker, D., E-mail: kgrasha@astro.umass.edu},
abstractNote = {We present a study of the hierarchical clustering of the young stellar clusters in six local (3–15 Mpc) star-forming galaxies using Hubble Space Telescope broadband WFC3/UVIS UV and optical images from the Treasury Program LEGUS (Legacy ExtraGalactic UV Survey). We identified 3685 likely clusters and associations, each visually classified by their morphology, and we use the angular two-point correlation function to study the clustering of these stellar systems. We find that the spatial distribution of the young clusters and associations are clustered with respect to each other, forming large, unbound hierarchical star-forming complexes that are in general very young. The strength of the clustering decreases with increasing age of the star clusters and stellar associations, becoming more homogeneously distributed after ∼40–60 Myr and on scales larger than a few hundred parsecs. In all galaxies, the associations exhibit a global behavior that is distinct and more strongly correlated from compact clusters. Thus, populations of clusters are more evolved than associations in terms of their spatial distribution, traveling significantly from their birth site within a few tens of Myr, whereas associations show evidence of disruption occurring very quickly after their formation. The clustering of the stellar systems resembles that of a turbulent interstellar medium that drives the star formation process, correlating the components in unbound star-forming complexes in a hierarchical manner, dispersing shortly after formation, suggestive of a single, continuous mode of star formation across all galaxies.},
doi = {10.3847/1538-4357/AA6F15},
journal = {Astrophysical Journal},
number = 2,
volume = 840,
place = {United States},
year = {Wed May 10 00:00:00 EDT 2017},
month = {Wed May 10 00:00:00 EDT 2017}
}
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