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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 and Claydon, Ian (2019) Globular cluster number density profiles using Gaia DR2 Monthly Notices of the Royal Astronomical Society, 485 (4). pp. 4906-4935.

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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.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Physics
Authors :
de Boer, T J
Hénault-Brunet, V
Sollima, A
Watkins, L L
Date : June 2019
Funders : European Research Council (ERC)
DOI : 10.1093/mnras/stz651
Copyright Disclaimer : © 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (
Uncontrolled Keywords : Methods: numerical. Stars: kinematics and dynamics. Globular clusters: general. Galaxies: star clusters.
Depositing User : Clive Harris
Date Deposited : 30 Aug 2019 13:22
Last Modified : 30 Aug 2019 13:22

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