SCYON Abstract

Received on April 23 2007

CCD BV survey of 42 open clusters

Authors	Gracjan Maciejewski and Andrzej Niedzielski
Affiliation	Centrum Astronomii Uniwersytetu Mikolaja Kopernika
Accepted by	Astronomy & Astrophysics
Contact	gm@astri.uni.torun.pl
URL	http://www.astri.uni.torun.pl/~gm
Links	Berkeley 4 / Berkeley 9 / Berkeley 10 / Berkeley 13 / Berkeley 15 / Berkeley 55 / Berkeley 67 / Berkeley 71 / Berkeley 85 / Berkeley 98 / Collinder 421 / Czernik 9 / Czernik 19 / Czernik 40 / Czernik 41 / Dias 1 / IC 4996 / King 1 / King 5 / King 6 / King 13 / King 13 / King 14 / King 16 / King 25 / NGC 146 / NGC 559 / NGC 884 / NGC 1027 / NGC 1513 / NGC 1798 / NGC 2126 / NGC 2168 / NGC 2192 / NGC 2266 / NGC 6885 / NGC 6939 / NGC 6996 / NGC 7654 / NGC 7762 / Skiff 1 / Tombaugh 4 / Tombaugh 5

Abstract

We present results of a photometric survey whose aim was to derive structural and astrophysical parameters for 42 open clusters. While our sample is definitively not representative of the total open cluster sample in the Galaxy, it does cover a wide range of cluster parameters and is uniform enough to allow for simple statistical considerations. BV wide-field CCD photometry was obtained for open clusters for which photometric, structural, and dynamical evolution parameters were determined. The limiting and core radii were determined by analyzing radial density profiles. The ages, reddenings, and distances were obtained from the solar metallicity isochrone fitting. The mass function was used to study the dynamical state of the systems, mass segregation effect and to estimate the total mass and number of cluster members. This study reports on the first determination of basic parameters for 11 out of 42 observed open clusters. The angular sizes for the majority of the observed clusters appear to be several times larger than the catalogue data indicate. The core and limiting cluster radii are correlated and the latter parameter is 3.2 times larger on average. The limiting radius increases with the cluster's mass, and both the limiting and core radii decrease in the course of dynamical evolution. For dynamically not advanced clusters, the mass function slope is similar to the universal IMF slope. For more evolved systems, the effect of evaporation of low-mass members is clearly visible. The initial mass segregation is present in all the observed young clusters, whereas the dynamical mass segregation appears in clusters older than about log(age) = 8. Low-mass stars are deficient in the cores of clusters older than log(age) = 8.5 and not younger than one relaxation time.