The HST Large Programme on ω Centauri. II. Internal Kinematics

Andrea Bellini, Mattia Libralato, Luigi R. Bedin, Antonino P. Milone, Roeland P.Van Der Marel, Jay Anderson, Daniel Apai, Adam J. Burgasser, Anna F. Marino, Jon M. Rees

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

In this second installment of the series, we look at the internal kinematics of the multiple stellar populations of the globular cluster ω Centauri in one of the parallel Hubble Space Telescope (HST) fields, located at about 3.5 half-light radii from the center of the cluster. Thanks to the over 15 yr long baseline and the exquisite astrometric precision of the HST cameras, well-measured stars in our proper-motion catalog have errors as low as ∼10 μas yr-1, and the catalog itself extends to near the hydrogen-burning limit of the cluster. We show that second-generation (2G) stars are significantly more radially anisotropic than first-generation (1G) stars. The latter are instead consistent with an isotropic velocity distribution. In addition, 1G stars have excess systemic rotation in the plane of the sky with respect to 2G stars. We show that the six populations below the main-sequence (MS) knee identified in our first paper are associated with the five main population groups recently isolated on the upper MS in the core of cluster. Furthermore, we find both 1G and 2G stars in the field to be far from being in energy equipartition, with for the former and for the latter, where η is defined so that the velocity dispersion scales with stellar mass as . The kinematical differences reported here can help constrain the formation mechanisms for the multiple stellar populations in ω Centauri and other globular clusters. We make our astro-photometric catalog publicly available.

Original languageEnglish (US)
Article number86
JournalAstrophysical Journal
Volume853
Issue number1
DOIs
StatePublished - Jan 20 2018

Fingerprint

Hubble Space Telescope
kinematics
stars
formation mechanism
catalogs
hydrogen
globular clusters
equipartition theorem
energy
proper motion
stellar mass
sky
programme
velocity distribution
cameras
radii
distribution

Keywords

  • Galaxy: kinematics and dynamics
  • globular clusters: individual (NGC 5139)
  • proper motions

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Bellini, A., Libralato, M., Bedin, L. R., Milone, A. P., Marel, R. P. V. D., Anderson, J., ... Rees, J. M. (2018). The HST Large Programme on ω Centauri. II. Internal Kinematics. Astrophysical Journal, 853(1), [86]. https://doi.org/10.3847/1538-4357/aaa3ec

The HST Large Programme on ω Centauri. II. Internal Kinematics. / Bellini, Andrea; Libralato, Mattia; Bedin, Luigi R.; Milone, Antonino P.; Marel, Roeland P.Van Der; Anderson, Jay; Apai, Daniel; Burgasser, Adam J.; Marino, Anna F.; Rees, Jon M.

In: Astrophysical Journal, Vol. 853, No. 1, 86, 20.01.2018.

Research output: Contribution to journalArticle

Bellini, A, Libralato, M, Bedin, LR, Milone, AP, Marel, RPVD, Anderson, J, Apai, D, Burgasser, AJ, Marino, AF & Rees, JM 2018, 'The HST Large Programme on ω Centauri. II. Internal Kinematics', Astrophysical Journal, vol. 853, no. 1, 86. https://doi.org/10.3847/1538-4357/aaa3ec
Bellini A, Libralato M, Bedin LR, Milone AP, Marel RPVD, Anderson J et al. The HST Large Programme on ω Centauri. II. Internal Kinematics. Astrophysical Journal. 2018 Jan 20;853(1). 86. https://doi.org/10.3847/1538-4357/aaa3ec
Bellini, Andrea ; Libralato, Mattia ; Bedin, Luigi R. ; Milone, Antonino P. ; Marel, Roeland P.Van Der ; Anderson, Jay ; Apai, Daniel ; Burgasser, Adam J. ; Marino, Anna F. ; Rees, Jon M. / The HST Large Programme on ω Centauri. II. Internal Kinematics. In: Astrophysical Journal. 2018 ; Vol. 853, No. 1.
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