SCYON Abstract

Received on July 23 2001

Photometric and Kinematic Studies of Open Star Clusters

AuthorsJörg Sanner
AffiliationSternwarte der Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
To appear inPhD summary


For this PhD thesis, 13 open star clusters were studied. The main goals were the determination of the parameters age, distance, and reddening of the clusters and their initial mass function (IMF) from the individual main-sequence turn-off point down to stellar masses of approx. 1 MO. To separate field and cluster stars we used a combination of membership probabilities derived from stellar proper motions and statistical field star subtraction. The IMF was determined with a maximum likelihood technique. The mass functions of all objects could be well represented by power laws with IMF indices ranging from Gamma=-0.69 (NGC 2541) to Gamma = -2.27 (Blanco 1), when Salpeter's (1955) value would be Gamma = -1.35. The differences in the indices are higher than statistically expected, indicating real IMF variations. With a survey of earlier IMF studies a weak dependence of the IMF index on the cluster age was detected. The IMF appears not to depend on other parameters like the location of the object within the Galaxy.