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Title: Hierarchical Star Formation in Turbulent Media: Evidence from Young Star Clusters

Abstract

We present an analysis of the positions and ages of young star clusters in eight local galaxies to investigate the connection between the age difference and separation of cluster pairs. We find that star clusters do not form uniformly but instead are distributed so that the age difference increases with the cluster pair separation to the 0.25–0.6 power, and that the maximum size over which star formation is physically correlated ranges from ∼200 pc to ∼1 kpc. The observed trends between age difference and separation suggest that cluster formation is hierarchical both in space and time: clusters that are close to each other are more similar in age than clusters born further apart. The temporal correlations between stellar aggregates have slopes that are consistent with predictions of turbulence acting as the primary driver of star formation. The velocity associated with the maximum size is proportional to the galaxy’s shear, suggesting that the galactic environment influences the maximum size of the star-forming structures.

Authors:
;  [1];  [2]; ;  [3]; ; ; ; ;  [4];  [5];  [6];  [7];  [8];  [9];  [10];  [11];  [12];  [13]
  1. Astronomy Department, University of Massachusetts, Amherst, MA 01003 (United States)
  2. IBM Research Division, T.J. Watson Research Center, Yorktown Heights, NY (United States)
  3. Department of Astronomy, The Oskar Klein Centre, Stockholm University, Stockholm (Sweden)
  4. Space Telescope Science Institute, Baltimore, MD (United States)
  5. California Institute of Technology, 1200 East California Boulevard, Pasadena, CA (United States)
  6. Department of Physics and Astronomy, University of Wyoming, Laramie, WY (United States)
  7. Institute for Computational Cosmology and Centre for Extragalactic Astronomy, Department of Physics, Durham University, Durham (United Kingdom)
  8. Department of Astronomy, University of Wisconsin–Madison, Madison, WI (United States)
  9. Zentrum für Astronomie der Universität Heidelberg, Institut für Theoretische Astrophysik, Albert-Ueberle-Str. 2, D-69120 Heidelberg (Germany)
  10. Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, Mönchhofstr. 12-14, D-69120, Heidelberg (Germany)
  11. Department of Astronomy, New Mexico State University, Las Cruces, NM (United States)
  12. Gemini Observatory, La Serena (Chile)
  13. Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia)
Publication Date:
OSTI Identifier:
22663527
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 842; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CORRELATIONS; FORECASTING; MILKY WAY; SPACE; STAR CLUSTERS; STARS; TURBULENCE; ULTRAVIOLET RADIATION; VELOCITY

Citation Formats

Grasha, K., Calzetti, D., Elmegreen, B. G., Adamo, A., Messa, M., Aloisi, A., Bright, S. N., Lee, J. C., Ryon, J. E., Ubeda, L., Cook, D. O., Dale, D. A., Fumagalli, M., Gallagher III, J. S., Gouliermis, D. A., Grebel, E. K., Kahre, L., Kim, H., and Krumholz, M. R., E-mail: kgrasha@astro.umass.edu. Hierarchical Star Formation in Turbulent Media: Evidence from Young Star Clusters. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA740B.
Grasha, K., Calzetti, D., Elmegreen, B. G., Adamo, A., Messa, M., Aloisi, A., Bright, S. N., Lee, J. C., Ryon, J. E., Ubeda, L., Cook, D. O., Dale, D. A., Fumagalli, M., Gallagher III, J. S., Gouliermis, D. A., Grebel, E. K., Kahre, L., Kim, H., & Krumholz, M. R., E-mail: kgrasha@astro.umass.edu. Hierarchical Star Formation in Turbulent Media: Evidence from Young Star Clusters. United States. doi:10.3847/1538-4357/AA740B.
Grasha, K., Calzetti, D., Elmegreen, B. G., Adamo, A., Messa, M., Aloisi, A., Bright, S. N., Lee, J. C., Ryon, J. E., Ubeda, L., Cook, D. O., Dale, D. A., Fumagalli, M., Gallagher III, J. S., Gouliermis, D. A., Grebel, E. K., Kahre, L., Kim, H., and Krumholz, M. R., E-mail: kgrasha@astro.umass.edu. Sat . "Hierarchical Star Formation in Turbulent Media: Evidence from Young Star Clusters". United States. doi:10.3847/1538-4357/AA740B.
@article{osti_22663527,
title = {Hierarchical Star Formation in Turbulent Media: Evidence from Young Star Clusters},
author = {Grasha, K. and Calzetti, D. and Elmegreen, B. G. and Adamo, A. and Messa, M. and Aloisi, A. and Bright, S. N. and Lee, J. C. and Ryon, J. E. and Ubeda, L. and Cook, D. O. and Dale, D. A. and Fumagalli, M. and Gallagher III, J. S. and Gouliermis, D. A. and Grebel, E. K. and Kahre, L. and Kim, H. and Krumholz, M. R., E-mail: kgrasha@astro.umass.edu},
abstractNote = {We present an analysis of the positions and ages of young star clusters in eight local galaxies to investigate the connection between the age difference and separation of cluster pairs. We find that star clusters do not form uniformly but instead are distributed so that the age difference increases with the cluster pair separation to the 0.25–0.6 power, and that the maximum size over which star formation is physically correlated ranges from ∼200 pc to ∼1 kpc. The observed trends between age difference and separation suggest that cluster formation is hierarchical both in space and time: clusters that are close to each other are more similar in age than clusters born further apart. The temporal correlations between stellar aggregates have slopes that are consistent with predictions of turbulence acting as the primary driver of star formation. The velocity associated with the maximum size is proportional to the galaxy’s shear, suggesting that the galactic environment influences the maximum size of the star-forming structures.},
doi = {10.3847/1538-4357/AA740B},
journal = {Astrophysical Journal},
number = 1,
volume = 842,
place = {United States},
year = {Sat Jun 10 00:00:00 EDT 2017},
month = {Sat Jun 10 00:00:00 EDT 2017}
}