Year: 2019
Type: article
Abstract: 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 is 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 generalised 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.
DOI: 10.1093/mnras/stz651
Authors: T J L de Boer, M Gieles, E Balbinot, V Hénault-Brunet, A Sollima, L L Watkins, I Claydon
Institutions: University of Hawaiʻi at Mānoa, University of Hawaii System, University of Surrey, Institució Catalana de Recerca i Estudis Avançats, Institut de Ciències del Cosmos, Universitat de Barcelona, University of Groningen, Herzberg Institute of Astrophysics, Osservatorio astronomico di Bologna, National Institute for Astrophysics, European Southern Observatory
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, Smithsonian Institution, National Aeronautics and Space Administration, Gordon and Betty Moore Foundation, Johns Hopkins University, Space Telescope Science Institute, European Space Agency, Royal Society, Queen's University Belfast, Durham University, Queen's University, National Central University, Eötvös Loránd Tudományegyetem, Smithsonian Astrophysical Observatory, Science Mission Directorate, Science and Technology Facilities Council, Planetary Science Division, Los Alamos National Laboratory, H2020 European Research Council
OpenAlex ID: W2911563418