Characterization of the praesepe star cluster by photometry and proper motions with 2MASS, PPMXL, and Pan-STARRS

P. F. Wang, W. P. Chen, C. C. Lin, A. K. Pandey, C. K. Huang, N. Panwar, C. H. Lee, M. F. Tsai, C. H. Tang, B. Goldman, W. S. Burgett, K. C. Chambers, P. W. Draper, H. Flewelling, T. Grav, J. N. Heasley, K. W. Hodapp, M. E. Huber, R. Jedicke, N. KaiserR. P. Kudritzki, G. A. Luppino, R. H. Lupton, E. A. Magnier, N. Metcalfe, D. G. Monet, J. S. Morgan, P. M. Onaka, P. A. Price, C. W. Stubbs, W. Sweeney, J. L. Tonry, R. J. Wainscoat, C. Waters

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


Membership identification is the first step in determining the properties of a star cluster. Low-mass members in particular could be used to trace the dynamical history, such as mass segregation, stellar evaporation, or tidal stripping, of a star cluster in its Galactic environment. We identified member candidates of the intermediate-age Praesepe cluster (M44) with stellar masses ∼0.11-2.4 M, using Panoramic Survey Telescope And Rapid Response System and Two Micron All Sky Survey photometry, and PPMXL proper motions. Within a sky area of 3° radius, 1040 candidates are identified, of which 96 are new inclusions. Using the same set of selection criteria on field stars, an estimated false positive rate of 16% was determined, suggesting that 872 of the candidates are true members. This most complete and reliable membership list allows us to favor the BT-Settl model over other stellar models. The cluster shows a distinct binary track above the main sequence, with a binary frequency of 20%-40%, and a high occurrence rate of similar mass pairs. The mass function is consistent with that of the disk population but shows a deficit of members below 0.3 solar masses. A clear mass segregation is evidenced, with the lowest-mass members in our sample being evaporated from this disintegrating cluster.

Original languageEnglish (US)
Article number57
JournalAstrophysical Journal
Issue number1
StatePublished - Mar 20 2014

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • open clusters and associations: individual (Praesepe)
  • stars: kinematics and dynamics
  • stars: luminosity function, mass function


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