CCD BV survey of 42 open clusters

Astronomy and Astrophysics (Impact Factor: 4.38). 04/2007; 467(3). DOI: 10.1051/0004-6361:20066588
Source: arXiv


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. Comment: 13 pages, 8 figures

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Available from: Andrzej T. Niedzielski, Oct 04, 2012
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    ABSTRACT: We establish the nature and derive fundamental and structural parameters of the recently catalogued objects FSR1744, FSR89 and FSR31. This work intends to provide clues to constrain the Galactic tidal disruption efficiency, improve statistics of the open cluster parameter space, and better define their age-distribution function inside the Solar circle. Properties of the objects are investigated by means of 2MASS colour-magnitude diagrams and stellar radial density profiles built with field star decontaminated photometry. Diagnostic-diagrams for structural parameters are used to help disentangle dynamical from high-background effects affecting such centrally projected open clusters. FSR1744, FSR89 and FSR31 are Gyr-class OCs located at Galactocentric distances 4.0 - 5.6kpc. Compared to nearby OCs, they have small core and limiting radii. With respect to the small number of OCs observed in the inner Galaxy, the emerging scenario in the near-infrared favours disruption driven by dynamical evolution rather than observational limitations associated with absorption and/or high background levels. Internally, the main processes associated with the dynamical evolution are, e.g. mass loss by stellar evolution, mass segregation and evaporation. Externally they are, e.g. tidal stress from the disk and bulge, and interactions with giant molecular clouds. FSR1744, FSR89 and FSR31 have structural parameters consistent with their Galactocentric distances, in the sense that tidally induced effects may have accelerated the dynamical evolution. Comment: 12 pages and 13 figs; A&A, accepted, July 9, 2007
    Astronomy and Astrophysics 07/2007; 473(2). DOI:10.1051/0004-6361:20077675 · 4.38 Impact Factor
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    ABSTRACT: In this paper research projects based on the wide-field CCD photometry performed in Piwnice Observatory are discussed. The used telescopes, as well as dedicated software pipeline for data reduction are presented. The prospects for collaboration between Polish and Bulgarian institutes in the field of wide-field photometry are also discussed.
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    ABSTRACT: Using homogeneous CCD photometric data from the 105-cm Kiso Schmidt telescope covering a 50' x 50' field, we study the mass functions (MFs) of nine open clusters. The ages and Galactocentric distances of the target clusters vary from 16 - 2000 Myr and 9-10.8 kpc, respectively. The values of MF slopes vary from -1.1 to -2.1. The classical value derived by Salpeter (1955) for the slope of the IMF is \Gamma = -1.35. The MFs in the outer regions of the clusters are found to be steeper than in the inner regions, indicating the presence of mass segregation in the clusters.The MF slopes (in the outer region as well as the whole cluster) undergo an exponential decay with the evolutionary parameter \tau (= age/ relaxation time). It seems that the evaporation of low-mass members from outer regions of the clusters is not significant at larger Galactocentric distances. It is concluded that the initial mass function (IMF) in the anticentre direction of the Galaxy might have been steeper than the IMF in the opposite direction. A comparison of the observed CMDs of the clusters with synthetic CMDs gives a photometric binary content of ~40%. Comment: Accepted for the publication in AJ, 21 Pages, 11 Figures, 9 Tables
    The Astronomical Journal 03/2008; 135(5). DOI:10.1088/0004-6256/135/5/1934 · 4.02 Impact Factor
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