Proper motion surveys of the young open clusters Alpha Persei and the Pleiades

N. R. Deacon, N. C. Hambly

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    44 Citations (Scopus)


    In this paper we present surveys of two open clusters using photometry and accurate astrometry from the SuperCOSMOS microdensitometer. These use plates taken by the Palomar Oschin Schmidt Telescope giving a wide field (5° from the cluster centre in both cases), accurate positions and a long time baseline for the proper motions. Distribution functions are fitted to proper motion vector point diagrams yielding formal membership probabilities. Luminosity and mass functions are then produced along with a catalogue of high probability members. Background star contamination limited the depth of the study of Alpha Per to R = 18. Due to this the mass function found for this cluster could only be fitted with a power law (ξ(m) = m) with α = 0.86-0.19+0.14. However with the better separation of the Pleiades' cluster proper motion from the field population results were obtained down to R = 21. As the mass function produced for this cluster extends to lower masses it is possible to see the gradient becoming increasingly shallow. This mass function is well fitted by a log normal distribution.

    Original languageEnglish
    Pages (from-to)125-136
    Number of pages12
    JournalAstronomy & Astrophysics
    Issue number1
    Publication statusPublished - Mar 2004


    • Astrometry
    • Galaxy: open clusters and associations: individual: Alpha Per, Pleiades
    • Stars: low mass, brown dwarfs


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