Massive open star clusters using the VVV survey III.
A young massive cluster at the far edge of the Galactic bar

S. Ramírez Alegría (1,2), J. Borissova (1,2), A.N. Chené (3), E. O'Leary (3), P. Amigo (1,2), D. Minniti (2,4), R. K. Saito (5), D. Geisler (6), R. Kurtev (1,2), M. Hempel (2,4), M. Gromadzki (1), J. R. A. Clarke (1), I. Negueruela (7), A. Marco (7), C. Fierro (1,8), C. Bonatto (9), M. Catelan (2,4)

(1) Instituto de Física y Astronomía, Universidad de Valparaíso, Chile; (2) The Millennium Institute of Astrophysics (MAS), Chile; (3) Gemini North Observatory, USA; (4) Pontificia Universidad Católica de Chile, Instituto de Astrofísica, Chile; (5) Universidade Federal de Sergipe, Departamento de Física, Brazil; (6) Departamento de Astronomía, Universidad de Concepción, Chile; (7) Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, Universidad de Alicante, Spain; (8) Escuela Superior de Física y Matemáticas del Instituto Politécnico Nacional, México; (9) Universidade Federal do Rio Grande do Sul, Departamento de Astronomia, Brazil

We present the third article in a series of papers focused on young and massive clusters discovered in the VVV survey. This article is dedicated to the physical characterization of VVV CL086, using part of its OB-stellar population.
We physically characterized the cluster using JHKs near-infrared photometry from ESO public survey VVV images, using the VVV-SkZ pipeline, and near-infrared K-band spectroscopy, following the methodology presented in the first article of the series.
Individual distances for two observed stars indicate that the cluster is located at the far edge of the Galactic bar. These stars, which are probable cluster members from the statistically field-star decontaminated CMD, have spectral types between O9 and B0 V. According to our analysis, this young cluster (1.0 Myr < age < 5.0 Myr) is located at a distance of 11 kpc, and we estimate a lower limit for the cluster total mass of (2.8·10^3) solar masses. It is likely that the cluster contains even earlier and more massive stars.

Reference: Astronomy & Astrophysics, Volume 564, id.L9, 4 pp
Status: Manuscript has been accepted