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Gaia and Hubble Unveil the Kinematics of Stellar Populations in the Type II Globular Clusters ? Centauri and M22

Cordoni, G. ; Milone, A. P. ; Marino, A. F. ; Da Costa, G. S. ; Dondoglio, E. ; Jerjen, H. ; Lagioia, E. P. ; Mastrobuono-Battisti, A. LU ; Norris, J. E. and Tailo, M. , et al. (2020) In Astrophysical Journal 898(2).
Abstract

The origin of multiple stellar populations in globular clusters (GCs) is one of the greatest mysteries of modern stellar astrophysics. N-body simulations suggest that the present-day dynamics of GC stars can constrain the events that occurred at high redshift and led to the formation of multiple populations. Here, we combine multiband photometry from the Hubble Space Telescope (HST) and ground-based facilities with HST and Gaia Data Release 2 proper motions to investigate the spatial distributions and the motions in the plane of the sky of multiple populations in the Type II GCs NGC 5139 (? Centauri) and NGC 6656 (M22). We first analyzed stellar populations with different metallicities. Fe-poor and Fe-rich stars in M22 share similar... (More)

The origin of multiple stellar populations in globular clusters (GCs) is one of the greatest mysteries of modern stellar astrophysics. N-body simulations suggest that the present-day dynamics of GC stars can constrain the events that occurred at high redshift and led to the formation of multiple populations. Here, we combine multiband photometry from the Hubble Space Telescope (HST) and ground-based facilities with HST and Gaia Data Release 2 proper motions to investigate the spatial distributions and the motions in the plane of the sky of multiple populations in the Type II GCs NGC 5139 (? Centauri) and NGC 6656 (M22). We first analyzed stellar populations with different metallicities. Fe-poor and Fe-rich stars in M22 share similar spatial distributions and rotation patterns and exhibit similar isotropic motions. Similarly, the two main populations with different iron abundance in ? Centauri share similar ellipticities and rotation patterns. When different radial regions are analyzed, we find that the rotation amplitude decreases from the center toward the external regions. Fe-poor and Fe-rich stars of ? Centauri are radially anisotropic in the central region and show similar degrees of anisotropy. We also investigate the stellar populations with different light-element abundances and find that their N-rich stars exhibit higher ellipticity than N-poor stars. In ? Centauri both stellar groups are radially anisotropic. Interestingly, N-rich, Fe-rich stars exhibit different rotation patterns than N-poor stars with similar metallicities. The stellar populations with different nitrogen of M22 exhibit similar rotation patterns and isotropic motions. We discuss these findings in the context of the formation of multiple populations.

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type
Contribution to journal
publication status
published
subject
in
Astrophysical Journal
volume
898
issue
2
article number
147
publisher
American Astronomical Society
external identifiers
  • scopus:85091756334
ISSN
0004-637X
DOI
10.3847/1538-4357/aba04b
language
English
LU publication?
yes
id
ba435bdc-aec4-4ddc-888b-4101b23ded69
date added to LUP
2020-11-04 07:31:16
date last changed
2023-01-01 01:31:27
@article{ba435bdc-aec4-4ddc-888b-4101b23ded69,
  abstract     = {{<p>The origin of multiple stellar populations in globular clusters (GCs) is one of the greatest mysteries of modern stellar astrophysics. N-body simulations suggest that the present-day dynamics of GC stars can constrain the events that occurred at high redshift and led to the formation of multiple populations. Here, we combine multiband photometry from the Hubble Space Telescope (HST) and ground-based facilities with HST and Gaia Data Release 2 proper motions to investigate the spatial distributions and the motions in the plane of the sky of multiple populations in the Type II GCs NGC 5139 (? Centauri) and NGC 6656 (M22). We first analyzed stellar populations with different metallicities. Fe-poor and Fe-rich stars in M22 share similar spatial distributions and rotation patterns and exhibit similar isotropic motions. Similarly, the two main populations with different iron abundance in ? Centauri share similar ellipticities and rotation patterns. When different radial regions are analyzed, we find that the rotation amplitude decreases from the center toward the external regions. Fe-poor and Fe-rich stars of ? Centauri are radially anisotropic in the central region and show similar degrees of anisotropy. We also investigate the stellar populations with different light-element abundances and find that their N-rich stars exhibit higher ellipticity than N-poor stars. In ? Centauri both stellar groups are radially anisotropic. Interestingly, N-rich, Fe-rich stars exhibit different rotation patterns than N-poor stars with similar metallicities. The stellar populations with different nitrogen of M22 exhibit similar rotation patterns and isotropic motions. We discuss these findings in the context of the formation of multiple populations. </p>}},
  author       = {{Cordoni, G. and Milone, A. P. and Marino, A. F. and Da Costa, G. S. and Dondoglio, E. and Jerjen, H. and Lagioia, E. P. and Mastrobuono-Battisti, A. and Norris, J. E. and Tailo, M. and Yong, D.}},
  issn         = {{0004-637X}},
  language     = {{eng}},
  number       = {{2}},
  publisher    = {{American Astronomical Society}},
  series       = {{Astrophysical Journal}},
  title        = {{Gaia and Hubble Unveil the Kinematics of Stellar Populations in the Type II Globular Clusters ? Centauri and M22}},
  url          = {{http://dx.doi.org/10.3847/1538-4357/aba04b}},
  doi          = {{10.3847/1538-4357/aba04b}},
  volume       = {{898}},
  year         = {{2020}},
}