Astronomy Letters

, Volume 38, Issue 2, pp 74–86 | Cite as

Investigation of the open star cluster NGC 2323 (M50) based on the proper motions and photometry of its constituent stars

  • V. N. FrolovEmail author
  • Yu. K. Ananjevskaja
  • E. V. Polyakov


The results of a comprehensive study of the Galactic open cluster NGC 2323 (M50) are presented. The positions of stars to a limiting magnitude {ie74-1} in a {ie74-2} area centered on the cluster were measured on six plates from the Pulkovo normal astrograph with a maximum epoch difference of 60 yr. The measurements were performed with the Pulkovo “Fantasy” automated measuring system upgraded in 2010. The corresponding areas from the USNO-A2.0, USNO-B1, and 2MASS catalogues were used as additional plates. As a result, the relative proper motions of stars were obtained with a root-mean-square error of 5.85 mas yr−1. A catalogue of UBV and JHK magnitudes for objects in the investigated area was compiled from available published resources. The astrometric selection of cluster members was made by the maximum likelihood method. A high individual cluster membership probability of a star (P ≥ 80%) served as the first selection criterion. The position of a star on the photometric color-magnitude (V ∝ (B-V), J ∝ (J-K)) diagrams of the cluster was considered as the second criterion. The position of an object on the color-color ((U-B)-(B-V), (J-H)-(J-K)) diagrams served as the third criterion. On the basis of these criteria, it was established that 508 stars are members of NGC 2323. These data were used to refine the physical parameters of the cluster: the mean reddening {ie74-3}, the true distance modulus {ie74-4}, and the cluster age of about 140 Myr from the grid of isochrones computed by the Padova group for solar chemical composition. Two tables contain the catalogues of proper motions and photometry for stars in the area. The luminosity and mass functions were constructed. The cluster membership of red and blue giants, variable, double, and multiple stars was considered. The position of the cluster center was improved: {ie74-5}, δ = −08°20′16″(2000.0).


open star clusters: NGC 2323 photometry proper motions 


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Copyright information

© Pleiades Publishing, Ltd. 2012

Authors and Affiliations

  • V. N. Frolov
    • 1
    Email author
  • Yu. K. Ananjevskaja
    • 1
  • E. V. Polyakov
    • 1
  1. 1.Pulkovo Astronomical ObservatoryRussian Academy of SciencesSt. PetersburgRussia

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