Letter to the Editor

The VISCACHA Survey

XII. SL 2: Age gap cluster in the southwestern Large Magellanic Cloud

¹ Departamento de Física, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais (UFMG), Av. Antônio Carlos 6627, Belo Horizonte 31270-901, Brazil
² Departamento de Ciencias Físicas, Instituto de Astrofísica, Facultad de Ciencias Exactas, Universidad Andres Bello (UNAB), Av. Fernandez Concha 700, 7591538 Las Condes, Santiago, Chile
³ Instituto de Física, Universidade Federal do Rio de Janeiro (UFRJ), Av. Athos da Silveira Ramos, 149, Rio de Janeiro 21941-909, Brazil
⁴ Departamento de Astronomia, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Osvaldo Aranha, s/n, Porto Alegre 91501-970, Brazil
⁵ Departamento de Ciências Exatas, Universidade Estadual de Santa Cruz (UESC), Rod.Jorge Amado km 16, 45662-900 Ilhéus, Brazil
⁶ Departamento de Estatística, Física e Matemática, Universidade Federal de São João del-Rei, Campus Alto Paraopeba, Rod. MG 443, km 7, Ouro Branco 36420-000, Brazil
⁷ Rubin Observatory Project Office, 950 N. Cherry Ave., Tucson, AZ 85719, USA
⁸ Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland
⁹ Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany
¹⁰ Instituto de Astronomía, Universidad Católica del Norte, Av. Angamos 0610, Antofagasta, Chile

^⋆ Corresponding author; plf.bernardo@gmail.com

Received: 18 December 2024
Accepted: 25 February 2025

Abstract

Context. In the Large Magellanic Cloud (LMC), only seven star clusters have been discovered to be older than ∼4 Gyr and younger than ∼10 Gyr, placing them in what is known as the age gap.

Aims. We aim to analyze the photometric data from the VISCACHA survey in the V and I bands to determine, for the first time, the astrophysical parameters of SL 2, revealing that the cluster is indeed situated within the age gap.

Methods. We used our newly developed SIESTA code to carry out a statistical isochrone fitting with synthetic color-magnitude diagrams (CMDs) to determine the cluster age, metallicity, distance, color excess, and binary fraction with two grids of stellar evolution models. In addition, the cluster mass was estimated based on its integrated magnitude.

Results. The ages obtained from isochrone fitting are compatible with the age gap, amounting to (7.17 ± 0.35) Gyr when using PARSEC-COLIBRI isochrones and (8.02 ± 0.45) Gyr when using MIST. Notably, SL 2 is the first age gap cluster discovered in the southern region of the LMC. The mass of the cluster is considerably smaller than that of the group of older LMC clusters.

Conclusions. SL 2 has a comparable metallicity to the other two age gap clusters with similar ages, namely, ESO 121-03 and KMHK 1592, as well as the LMC field star population. While the discovery of a new cluster with such characteristics could be seen as evidence that age gap clusters were formed in situ, the heliocentric distance of SL2 locates it far from the LMC center, akin to the SMC distance. Therefore, the question of its origin, alongside that of other age gap clusters, remains unresolved and open to further investigation.