On the self-consistent physical parameters of LMC intermediate-age clusters

TL;DR

This study derives self-consistent physical parameters for 15 LMC intermediate-age clusters using HST data and compares different stellar models, revealing model-dependent trends and confirming the clusters' distribution aligns with the LMC disk.

Contribution

It provides a comprehensive analysis of LMC clusters' parameters using multiple stellar evolutionary models, highlighting the importance of overshooting treatments and validating metallicity estimates.

Findings

Models with overshooting yield more reliable parameters.

Derived metallicities agree with spectroscopic data.

Cluster distribution aligns with the LMC thick disk.

Abstract

The LMC clusters are unique templates of simple stellar population (SSP), being crucial to calibrate models describing the integral light as well as to test the stellar evolution theory. With this in mind we analyzed HST/WFPC2 (V, B--V) colour-magnitude diagrams (CMDs) of 15 populous LMC clusters with ages between ~0.3 Gyr and ~4 Gyr using different stellar evolutionary models (Padova, PEL or Pisa, BaSTI or Teramo). Following the approach described by Kerber, Santiago & Brocato (2007), we determined accurate and self-consistent physical parameters (age, metallicity, distance modulus and reddening) for each cluster by comparing the observed CMDs with synthetic ones. We found significant trends in the physical parameters due to the choice of stellar evolutionary model and treatment of convective core overshooting. In general, models that incorporate overshooting presented more reliable results than those that do not. Comparisons with the results found in the literature demonstrated that our derived metallicities are in good agreement with the ones from the spectroscopy of red giants. We also confirmed that, independent of the adopted stellar evolutionary library, the recovered 3D distribution for these clusters is consistent with a thick disk roughly aligned with the LMC disk as defined by field stars. Finally, we also provide new estimates of distance modulus to the LMC center, that are marginally consistent with the canonical value of 18.50.