[1] Univ Valparaiso, Fac Ciencias, Dept Fis & Astron, Casilla 5030, Valparaiso, Chile
[2] Milky Way Millennium Nucleus, Santiago 7820436, Chile
[3] Univ Nacl Autonoma Mexico, Inst Astron, Mexico City 04510, DF, Mexico
[4] Univ Cincinnati, Dept Phys, Cincinnati, OH 45221 USA
[5] European So Observ, Santiago 19001, Chile
[6] Univ Pittsburgh, Dept Phys & Astron, Pittsburgh, PA 15260 USA
[7] Inst Politecn Nacl, Escuela Super Fis & Math, Mexico City, DF, Mexico