Globular Clusters

Title: Inspection of 19 globular cluster candidates in the Galactic bulge with the VVV survey

Garro, Elisa Rita

E. R. Garro(1), D. Minniti(1;2), M. Gómez(1), J. Alonso-García(3;4), V. Ripepi(5), J. G. Fernández-Trincado(6), and F. Vivanco Cádiz(1)

(1) Departamento de Ciencias Físicas, Facultad de Ciencias Exactas, Universidad Andres Bello, Fernández Concha 700, Las Condes, Santiago, Chile

(2) Vatican Observatory, Vatican City State, V-00120, Italy

(3) Centro de Astronomía (CITEVA), Universidad de Antofagasta, Av. Angamos 601, Antofagasta, Chile

(4) Millennium Institute of Astrophysics, Nuncio Monseñor Sotero Sanz 100, Of. 104, Providencia, Santiago, Chile

(5) INAF-Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, 80131 Naples, Italy

(6) Instituto de Astronomía, Universidad Católica del Norte, Av. Angamos 0610, Antofagasta, Chile

Abstract: The census of the globular clusters (GCs) in the Milky Way (MW) is still a work in progress. We explore the nature of 19 new GC candidates in the Galactic bulge, based on the analysis of their color-magnitude diagrams (CMDs) in the near-IR (NIR), using the VISTA Variables in the Via Láctea Survey (VVV) database. We estimate their main astrophysical parameters: reddening, extinction, distance, luminosity, mean cluster proper motions (PMs), metallicity and age. We obtain the cluster catalogues including the likely cluster members by applying a decontamination procedure on the observed CMDs, based upon the vector PM diagrams. We adopt NIR reddening maps in order to calculate the reddening and extinction for each cluster, and then estimate the distance moduli and heliocentric distances. Metallicities and ages are evaluated by fitting theoretical stellar isochrones. We calculate their luminosities in comparison with known Galactic GCs. We examine the possible RR Lyrae members found in the cluster fields. Based on our analysis, we conclude that 9 candidates are real GCs, 7 need more observations to be fully confirmed as GCs, and 3 candidates are discarded for being younger open clusters.

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