Low Mass Stars and Brown Dwarfs in Praesepe

Abstract

Presented are the results of a large and deep optical-near-infrared multi-epoch survey of the Praesepe open star cluster using data from the UKIDSS Galactic Clusters Survey. Multiple colour magnitude diagrams were used to select potential members and proper motions were used to assign levels of membership probability. From our sample, 145 objects were designated as high probability members (p >= 0.6) with most of these having been found by previous surveys although 14 new cluster members are also identified. Our membership assignment is restricted to the bright sample of objects (Z < 18). From the fainter sample, 39 candidates were found from an examination of multiple colour magnitude plots. Of these, 2 have small but significant membership probabilities. Finally, using theoretical models, cluster luminosity and mass functions were plotted with the later being fitted with a power law of alpha = 1.11 +/- 0.37 for the mass range 0.6 to 0.125 Msun and an assumed cluster age of 500 Myrs in the UKIDSS Z photometric band. Likewise taking an assumed cluster age of 1 Gyr we find alpha = 1.10 +/- 0.37. Similar values were also found for the J and K bands. These results compare favourably with the result of Kraus & Hillenbrand (2007) (alpha = 1.4 +/- 0.2) but are significantly lower than that of the more recent study conducted by Boudreault et al. (2009) (alpha = 1.8 +/- 0.1).

21 pages, 11 figures, 3 tables and 4 appendices. Accepted for publication in MNRAS, corrected a missing reference

References in corpus (9)

• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• The WFCAM Science Archive
• The UKIRT Wide Field Camera ZYJHK Photometric System: Calibration from 2MASS
• The Stellar Populations of Praesepe and Coma Berenices
• New brown dwarfs in Upper Sco using UKIDSS Galactic Cluster Survey science verification data
• Proper motion L and T dwarf candidate members of the Pleiades
• Proper motions of field L and T dwarfs
• A search for substellar members in the Praesepe and sigma Orionis clusters
• L dwarfs in the Hyades

Cited by in corpus (15)

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• Rotation of Late-Type Stars in Praesepe with K2
• Astrometric and photometric initial mass functions from the UKIDSS Galactic Clusters Survey: I The Pleiades
• Testing the universality of the IMF with Bayesian statistics: young clusters
• Wide binaries are rare in open clusters
• The stellar mass function, binary content and radial structure of the open cluster Praesepe derived from PPMXL and SDSS data
• Astrometric and photometric initial mass functions from the UKIDSS Galactic Clusters Survey: III Praesepe
• Characterization of the Praesepe Star Cluster by Photometry and Proper Motions with 2MASS, PPMXL, and Pan-STARRS
• The family pictures of our neighbours: investigating the mass function and dynamical parameters of nearby open clusters
• The mass function of IC4665 revisited by the UKIDSS Galactic Clusters Survey
• A photometric and astrometric investigation of the brown dwarfs in Blanco 1
• Low-mass and sub-stellar eclipsing binaries in stellar clusters
• Two close binaries across the hydrogen-burning limit in the Praesepe open cluster