Star Clusters and Associations

Abstract

The last three years have been very productive for cluster research. More than 450 references for open clusters and more than 800 for globular clusters have been collected from the literature and Astronomy and Astrophysics Abstracts (Vol. 52 to 56). The observations present very broad scope thanks to the new instrumental facilities like infrared arrays and the X-ray and IR satellites. Our knowledge of how and where open clusters form has been considerably advanced with the advent of infrared arrays images which has revealed the presence of compact, centrally condensed clusters of newly formed stars embedded in, or closely associated with dense cores of giant molecular clouds. The present report tries to survey the activity in these domains, summarize the results and trends, and collect the information on the observed clusters and associations. But, owing to the large number of references, it is not possible to quote every paper. A higher priority has been given to the new data obtained for star clusters, which should help everybody to be easily informed of the observations made during the past three years. Therefore the traditional form of the report has been largely maintained. Abstracts and papers in conference proceedings have usually not been quoted here to save place and no attempt has been made to include unpublished material. For complete bibliographic information, the Astronomy and Astrophysics Abstracts, chapters 121 (young stellar objects), 131 (star formation), 152 (stellar associations), 153 (open clusters), 154 (globular clusters), and 156 (Magellanic Clouds) remain the best source. To improve the efficiency of literature retrieval, it would be important that the first keyword refers to open, respectively globular clusters, whatever the observational data may be (proper motions, radial velocity, photometry and so on). The database for stars in open clusters (Mermilliod 1992) offers an up-to-date bibliographic search facility based on keywords. Murtagh and Adorf (1993) have given a short report of the astronomical literature publicly accessible on-line. The subject of low-mass star formation in southern molecular clouds has been reviewed in a comprehensive ESO report edited by Reipurth (1991), which provides extensive references to the literature.