A Catalogue of infrared star clusters and stellar groups

Abstract

Abstract. We compiled a catalogue of infrared star clusters in the Galaxy, which are most of them embedded. It condenses the growing literature information. We also include in the sample infrared stellar groups which are less dense than star clusters, such as those embedded in the dark clouds Taurus-Auriga and Chamaleon I. We provide galactic and equatorial coordinates, angular dimensions, different designations and related objects such as nebulae. A total of 189 infrared clusters and 87 embedded stellar groups are included. A fraction of 25% of the embedded clusters are projected close to each other in pair or triplet systems, indicating that multiplicity plays an important role in star cluster formation.

Does Cyg OB2 harbour any open cluster?

“…Recently, Le Duigou & Knödlseder (2002), also using 2MASS observations, studied the morphology and stellar content of 22 embedded clusters in Cygnus X, some of them new. All these findings correspond to infrared clusters and stellar groups (Bica et al 2003). An interesting issue is whether any optical or infrared open cluster remains uncatalogued in the area.…”

“…10 together with Objects 1 and 2 and all previously reported objects in the area. Several embedded clusters or stellar groups have been reported in the surroundings of Cyg OB2, as can be seen in the recent catalogue by Bica et al (2003) which is basically complete to mid 2002. We also included the new objects by Le Duigou & Knödlseder (2002), which are indicated by LK in Fig.…”

“…However, even assuming that their luminosity functions have a cutoff near A0, the two objects would still be very interesting aggregates of high and intermediatemass stars, in a region where low-mass star formation would have been inhibited. Their angular diameters of 4 and 5 , at a distance of 1.8 kpc, convert to linear diameters of 2.1 and 2.6 pc, respectively, comparable to those of infrared embedded clusters (Bica et al 2003).…”

“…Dutra & Bica (2001) found new embedded clusters and stellar groups in the direction of known optical and radio nebulae in the Galaxy, including the Cygnus X area, using the Two Micron All Sky Survey (hereafter 2MASS, Skrutskie et al 1997). Embedded stellar groups are less dense than clusters but appear to be physical systems (Bica et al 2003). Dutra & Bica (2001) studied colour-magnitude diagrams (CMDs) using the 2MASS Point Source Catalogue and obtained distances in the range 1.0 < d (kpc) < 1.8 for 7 Cygnus X clusters.…”

Discovering protostars and their host clusters via WISE

“…1), cluster dissolution timescale ('infant mortality rate' for protoclusters, Lada & Lada 2003), and the Galaxy's spiral structure. Bonatto & Bica (2011) examined newly identified clusters (e.g., Bica et al 2003) and inferred that the local star formation rate is not constant and is punctuated for τ ≤ 9 and 220-600 Myr, while Spitzer legacy results for five nearby protostar-hosting complexes imply that a sizable fraction of the YSOs lie in loose clusters (n > 35, ρ > 1M ⊙ /pc 3 , Evans et al 2009). Such pertinent determinations may be invariably strengthened by increasing the statistics of known protostars and protoclusters.…”