Abstract. We carried out a 2MASS J, H and K s survey of infrared star clusters in the Milky Way sector 230• < < 350• . This zone was the least studied in the literature, previously including only 12 infrared clusters or stellar groups with |b| < 10• , according to the recent catalogue by Bica et al. (2003). We concentrated efforts on embedded clusters, which are those expected in the areas of known radio and optical nebulae. The present study provides 179 new infrared clusters and stellar groups, which are interesting targets for detailed future infrared studies. The sample of catalogued infrared clusters and stellar groups in the Galaxy is now increased by 63%.

Abstract. We carried out a survey of infrared star clusters and stellar groups on the 2MASS J, H and K s all-sky release Atlas in the Northern and Equatorial Milky Way (350The search in this zone complements that in the Southern Milky Way (Dutra et al. 2003a). The method concentrates efforts on the directions of known optical and radio nebulae. The present study provides 167 new infrared clusters, stellar groups and candidates. Combining the two studies for the whole Milky Way, 346 infrared clusters, stellar groups and candidates were discovered, whereas 315 objects were previously known. They constitute an important new sample for future detailed studies.

Abstract. We employed J, H and Ks photometry from the 2MASS Catalogue to study the embedded star clusters in the nebulae NGC 2327 and BRC 27 locate in the molecular cloud Canis Majoris R1. We made use of colourcolour and colour-magnitudes diagrams of the sample objects in conjunction with those of the Trapezium cluster which was used as a template, together with theoretical isochrones. The fundamental parameters were derived for the clusters. The distances found for NGC 2327 and BRC 27 were 1.2 kpc which are compatible with previous distances for the complex. The estimated ages are based mostly on the number of stars with anomalous colours, supposedly of types Herbig AeBe and T Tauri. Both embedded clusters have ages of ≈1.5 Myr. The results suggest the birth of a physical pair of star clusters in CMaR1.

Abstract. An analysis of the candidate embedded stellar systems in the reflection nebulae vdBH- RN 26, GGD 20, and NGC 6595 is presented. Optical spectroscopic data from CASLEO (Argentina) in conjunction with near infrared photometry from the 2MASS Point Source Catalogue were employed. The analysis is based on source surface density, colour-colour and colour-magnitude diagrams together with theoretical pre-main sequence isochrones. We take into account the field population affecting the analysis by carrying out a statistical subtraction. The fundamental parameters for the stellar systems were derived. The resulting ages are in the range 1−4 Myr and the objects are dominated by pre-main sequence stars. The observed masses locked in the clusters are less than 25 M . The studied systems have no stars of spectral types earlier than B, indicating that star clusters do not necessarily evolve through an HII region phase. The relatively small locked mass combined with the fact that they are not numerous in catalogues suggests that these low mass clusters are not important donors of stars to the field populations.

Aims. Among the star clusters in the Galaxy, those embedded in nebulae represent the youngest group, which has only recently been explored. The analysis of a sample of 22 candidate embedded stellar systems in reflection nebulae and/or HII environments is presented. Methods. We employed optical spectroscopic observations of stars in the directions of the clusters carried out at CASLEO (Argentina) together with near infrared photometry from the 2MASS catalogue. Our analysis is based on source surface density, colour−colour diagrams and on theoretical pre-main sequence isochrones. We take into account the field star contamination by carrying out a statistical subtraction. Results. The studied objects have the characteristics of low mass systems. We derive their fundamental parameters. Most of the cluster ages are younger than 2 Myr. The studied embedded stellar systems in reflection nebulae and/or HII region complexes do not have stars of spectral types earlier than B. The total stellar masses locked in the clusters are in the range 20−220 M . They are found to be gravitationally unstable and are expected to dissolve in a timescale of a few Myr.