Discovery of new Milky Way star cluster candidates in the 2MASS Point Source Catalog IV. Follow-up observations of cluster candidates in the Galactic plane

Abstract

Nearly 500 cluster candidates have been reported by searches based on the new all-sky near infrared surveys. The true nature of the majority of these objects is still unknown. This project aims to estimate the physical parameters of some of the candidates in order to use them as probes of the obscured star formation in the Milky Way. Here we report deep near infrared observations of four objects, discovered by our search based on the 2MASS Point Source Catalog (Ivanov et al. 2002; Borissova et al. 2003). CC04 appears to be a few million year old cluster. We estimate its distance and extinction, and set a limit on the total mass. CC08 contains red supergiants, indicating a slightly older age of about 7-10 Myr. The suspected cluster nature of CC13 was not confirmed. CC14 appears to be an interesting candidate with double-tail-like morphology but our data doesn't allow us to derive a firm conclusion about the nature of this object. We found no supermassive star clusters similar to the Arches or the Quintuplet (Mtot >= 10**4 Msolar) among the dozen confirmed clusters studied so far in this series of papers, indicating that such objects are not common in the Milky Way.