Globular cluster number density profiles using Gaia DR2

de Boer, T. J. L., Gieles, M., Balbinot, E., Hénault-Brunet, V., Sollima, A., Watkins, L. L. & Claydon, I., 1-Jun-2019, In : Monthly Notices of the Royal Astronomical Society. 485, 4, p. 4906-4935 30 p.

Research output: Contribution to journalArticleAcademicpeer-review

  • T. J. L. de Boer
  • M. Gieles
  • E. Balbinot
  • V. Hénault-Brunet
  • A. Sollima
  • L. L. Watkins
  • I. Claydon
Using data from Gaia DR2, we study the radial number density profiles of the Galactic globular cluster sample. Proper motions are used for accurate membership selection, especially crucial in the cluster outskirts. Due to the severe crowding in the centres, the Gaia data are supplemented by literature data from HST and surface brightness measurements, where available. This results in 81 clusters with a complete density profile covering the full tidal radius (and beyond) for each cluster. We model the density profiles using a set of single-mass models ranging from King and Wilson models to generalized lowered isothermal LIMEPY models and the recently introduced SPES models, which allow for the inclusion of potential escapers. We find that both King and Wilson models are too simple to fully reproduce the density profiles, with King (Wilson) models on average underestimating (overestimating) the radial extent of the clusters. The truncation radii derived from the LIMEPY models are similar to estimates for the Jacobi radii based on the cluster masses and their orbits. We show clear correlations between structural and environmental parameters, as a function of Galactocentric radius and integrated luminosity. Notably, the recovered fraction of potential escapers correlates with cluster pericentre radius, luminosity, and cluster concentration. The ratio of half mass over Jacobi radius also correlates with both truncation parameter and PE fraction, showing the effect of Roche lobe filling.
Original languageEnglish
Pages (from-to)4906-4935
Number of pages30
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
Publication statusPublished - 1-Jun-2019


  • methods: numerical, stars: kinematics and dynamics, globular clusters: general, galaxies: star clusters, Astrophysics - Astrophysics of Galaxies

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