Ca II triplet spectroscopy of Small Magellanic Cloud red giants VI: Analysis of chemical properties of the main body

• Autores: de Bórtoli, Bruno Javier; Parisi, Maria Celeste; Bassino, Lilia Patricia; Geisler, Doug; Dias, Bruno; Gimeno, G.; Dangelo Farto, Marcela Silvina; Mauro, F.
• Año de publicación: 2022
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: GALAXIES: STAR CLUSTERS: GENERAL; MAGELLANIC CLOUDS; STARS: ABUNDANCES
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

Aims. In this paper we analyze the chemical evolution of the main body of the SMC, adding six additional clusters to previously published samples, based on homogeneously determined and accurate metallicities. Methods. We derived radial velocities and Ca II Triplet (CaT) metallicity of more than 150 red giants stars in six SMC star clusters and their surrounding fields, with the instrument GMOS on GEMINI-S. The mean cluster radial velocity and metallicity were obtained with mean errors of 2.2 km s-1 and 0.03 dex, while the mean field metallicities have a mean error of 0.13 dex. We add this information to that available for another 51 clusters and 30 fields with CaT metallicities on the same scale. Using this expanded sample we analyze the chemical properties of the SMC main body, defined as the inner 3.4◦ in semimajor axis. Results. We found a high probability that the metallicity distribution of the main body clusters is bimodal with a metal-rich and a metal-poor cluster group, having mean metallicities with a dispersion of µ = -0.80, σ = 0.06 and µ = -1.15, σ = 0.10 dex, respectively. On the other hand, main body field stars show a unimodal metallicity distribution peaking at [Fe/H] ∼ -1 and dispersion of 0.3. Neither metal-rich nor metal-poor clusters present a metallicity gradient. However, the full main body cluster sample and field stars have a negative metallicity gradient consistent with each other, but the one corresponding to clusters has a large error due to the large metallicity dispersion present in the clusters studied in that region. Metal-rich clusters present a clear age–metallicity relation, while metal-poor clusters present no chemical enrichment throughout the life of the galaxy. Conclusions. We present observational evidence that the chemical enrichment is complex in the SMC main body. Two cluster groups with potential different origins could be coexisting in the main body. More data with precise and homogeneous metallicities and distances are needed and dynamical simulations are required to understand the possible different origins for the two cluster groups.
Fil: de Bórtoli, Bruno Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentina
Fil: Parisi, Maria Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; Argentina
Fil: Bassino, Lilia Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentina
Fil: Geisler, Doug. Universidad de La Serena; Chile. Universidad de Concepción; Chile
Fil: Dias, Bruno. Universidad de Tarapacá; Chile
Fil: Gimeno, G.. No especifíca;
Fil: Dangelo Farto, Marcela Silvina. No especifíca;
Fil: Mauro, F.. Universidad Católica del Norte; Chile