EPJ Web of Conferences 16, 06011 (2011)
https://doi.org/10.1051/epjconf/20111606011

The stellar and substellar mass function in central region of the old open cluster Praesepe from deep LBT observations

¹ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
² Departamento de Astrofísica, Facultad de Física, Universidad Complutense de Madrid, 28040 Madrid, Spain

^a e-mail: wwang@mpia.de

Abstract

Studies of the mass function of open clusters of different ages allow us to study the efficiency with which brown dwarfs are evaporated from clusters to populate the field. Surveys in relatively old clusters (age ≳100 Myr) do not suffer from problems found in young clusters, such as intra-cluster extinction and large uncertainties in brown dwarf models. In this paper, we present the results of a photometric survey to study the mass function of the old open cluster Praesepe (age of ~590 Myr and distance of ~190 pc), down to the substellar regime. We have performed optical (riz and Y-band) photometric survey of Praesepe with the Large Binocular Telescope Camera, for a spatial coverage of 0.61 deg² from ~90 M_J down to a 5σ detection limit at 40 M_J.