CCD BV survey of 42 open clusters

Astronomy and Astrophysics (Impact Factor: 4.48). 04/2007; DOI: 10.1051/0004-6361:20066588
Source: arXiv

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. Comment: 13 pages, 8 figures

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We present here our first series in studying the astrophysical parameters of the open cluster "Ruprecht 15" using PPMXL1 database. In this context, the photometric, astrometry and statistical parameters for this cluster (limited radius, core and tidal radii, distances, membership, reddening, age, luminosity function, mass function, total mass, and the dynamical relaxation time) are determined for the first time.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Context: We investigate the nature of a sample of star cluster candidates detected as stellar overdensities towards the Galactic anticentre. Aims: Taken from the catalogue of Froebrich, Scholz, and Raftery (FSR), the sample contains 28 star cluster candidates located within |Δℓ|=20° of the anticentre. These are all the candidates in that sector classified by FSR with a high probability of being star clusters. Our main goals are to determine the fraction of such candidates that are unknown star clusters, to derive their astrophysical parameters, and to investigate the relationship of cluster parameters with position in the Galaxy. Methods: Properties of the star cluster candidates are investigated with field-star decontaminated 2MASS colour-magnitude diagrams and stellar radial density profiles. Results: All candidates present significant excesses in the radial density profiles, consistent with the method from which they were originally selected. Of the 28 candidates, 7 are previously known open clusters, 2 have been recently identified, and 6 are new ones with ages from 30 Myr to 1 Gyr. Among the remaining 13 candidates, 6 are uncertain cases that require deeper observations, while 7 appear to be important field fluctuations. The structure of part of the newly identified open clusters appears to be affected by interaction with giant molecular clouds in the Local and Perseus arms. Conclusions: When photometric and radial distribution properties are considered together, an important fraction of the stellar overdensities with a fluctuation level ⪆3σ are shown to be star clusters. Thus, catalogues of star cluster candidates, coupled to the present kind of study, are an important source for identifying unknown open clusters. Such efforts affect the understanding of the star-formation rate, cluster dynamical evolution, and Galactic structure, among others.
    Astronomy and Astrophysics 07/2008; 485(1):81-93. · 4.48 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A characteristic of the structure and the evolution of open clusters is presented in this short review. Simple methods for analysing both issues are sketched and the literature references are given.
    Bulgarian Astronomical Journal. 01/2009;

Full-text (2 Sources)

Available from
May 22, 2014