Metallicities and ages for star clusters and their surrounding fields in the Large Magel- lanic Cloud

W. NARLOCH, G. PIETRZYNSKI, W. GIEREN, A.E. PIATTI, + 14 COAUTORES

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2022 vol. 666 p. 1 - 39

0004-6361

Aims. We study 147 star clusters in the Large Magellanic Cloud (LMC) in order to determine their mean metallicities and ages, as well as the mean metallicities of 80 surrounding fields. We construct an age–metallicity relation (AMR) for the clusters in the LMC. Methods. For this purpose, we use Strömgren photometry obtained with SOI camera on the 4.1 m SOAR telescope. We derive metallicities of individual stars utilizing a calibration of Strömgren (b − y) and m1 colors with metallicites from the literature. Cluster ages are determined from the isochrone fitting.Results. We find the mean metallicity and age for 110 star clusters and for the remaining 37 we provide an age estimation only. To the best of our knowledge, for 29 clusters from our sample we provide both metallicity and age for the first time, while for 66 clusters we provide a first determination of the metallicity, and for 43 clusters the first estimation of the age. We also calculate the mean metallicities for stars from 80 fields around the clusters. The results are then analyzed for spatial metallicity and age distributions of clusters in the LMC, as well as AMR for them. The old, metal-poor star clusters occur both in and out of the LMC bar region, while intermediate-age clusters are located mostly outside of the bar. The majority of star clusters younger than 1 Gyr are located in the bar region. We find good agreement between our AMR and theoretical models of the LMC chemical enrichment, as well as with AMRs for clusters from the literature. Next, we take advantage of 26 stellar clusters from our sample which host Cepheid variables and use them as an independent check of the correctness of our age determination procedure. We use period–age relations for Cepheids to calculate the mean age of a given cluster and compare it with the age obtained from isochrone fitting. We find good agreement between these ages especially for models taking into account additional physical processes, e.g., rotation. We also compare the AMR of the LMC and SMC derived in a uniform way, and note that they indicate possible former interaction between these two galaxies. The Strömgren photometry obtained for this study is made publicly available.