Cool Stars 14 - Submitted Abstract # 147
This version created on 05 October 2006

A precise, deep determination of the substellar mass function in the
open cluster IC 2391


Steve Boudreault, Max-Planck-Institut für Astronomie
Coryn Bailer-Jones, Max-Planck-Institut für Astronomie

The formation mechanism of brown dwarfs and its relation to star and
planet formation remains an open issue.  A careful determination of
the substellar mass function in open clusters at different ages and
environments is one of the primary methods for addressing this.  Using
the Wide Field Imager (WFI) at the ESO 2.2m telescope at La Silla, we
have performed an extensive, multiband photometric survey of the open
cluster IC 2391 (age ~ 50  Myr, distance ~ 146 pc).  This survey was
carried out in two parts :  4 WFI deep fields in the central part of
the cluster and 31 WFI fields from radial part, for a total coverage
of ~11.9 square degree.  Here we present preliminary results of this
survey and our candidate selection, based on observations and
theoretical isochrones placed in color--magnitude and color--color
diagrams.  We will perform follow-up spectroscopy to determine their
spectral type, confirm or refute cluster membership case-by-case and
estimate their model-based masses.

----------------------------------