Star density profiles of six old star clusters in the Large Magellanic   Cloud

B. Lanzoni (1,2); F. R. Ferraro (1,2); E. Dalessandro (2); M. Cadelano; (1,2); C. Pallanca (1,2); S. Raso (1,2); A. Mucciarelli (1,2); G. Beccari; (3); and P. Focardi (1) - (1 Bologna University; Italy; (2) INAF-OAS,; Bologna; Italy; (3) ESO; Germany)

arXiv:1911.01928·astro-ph.GA·January 8, 2020

Star density profiles of six old star clusters in the Large Magellanic Cloud

B. Lanzoni (1,2), F. R. Ferraro (1,2), E. Dalessandro (2), M. Cadelano, (1,2), C. Pallanca (1,2), S. Raso (1,2), A. Mucciarelli (1,2), G. Beccari, (3), and P. Focardi (1) - (1 Bologna University, Italy, (2) INAF-OAS,, Bologna, Italy, (3) ESO, Germany)

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TL;DR

This study uses Hubble Space Telescope data to analyze the density profiles of six old star clusters in the Large Magellanic Cloud, revealing new structural parameters and correlations with dynamical age.

Contribution

It provides updated center positions and density profiles for six LMC clusters, with improved modeling and analysis of their structural parameters.

Findings

01

Cluster density profiles fit well with King models

02

Derived centers differ from previous measurements by several arcseconds

03

Anti-correlation between radius ratio and dynamical age

Abstract

We used resolved star counts from Hubble Space Telescope images to determine the center of gravity and the projected density profiles of 6 old globular clusters in the Large Magellanic Cloud (LMC), namely NGC 1466, NGC 1841, NGC 1898, NGC 2210, NGC 2257 and Hodge 11. For each system, the LMC field contribution was properly taken into account by making use, when needed, of parallel HST observations. The derived values of the center of gravity may differ by several arcseconds (corresponding to more than 1 pc at the distance of the LMC) from previous determinations. The cluster density profiles are all well fit by King models, with structural parameters that may differ from the literature ones by even factors of two. Similarly to what observed for Galactic globular clusters, the ratio between the effective and the core radii has been found to anti-correlate with the cluster dynamical age.

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