A Brown Dwarf Candidate in the Praesepe Open Cluster

We present optical and infrared observations of Roque Praesepe 1 (RPr 1), a faint (I = 21.01) and very red object (I-K = 4.57) discovered in a deep CCD survey, covering an area of 800 arcmin2 of the Praesepe open cluster. A low-resolution spectrum shows that RPr 1 is a very late object, the latest object in Praesepe for which a spectrum has been taken to date. Our estimates give a mass between 0.063 and 0.084 M☉ and indicate that RPr 1 may turn out to be the first brown dwarf in this cluster.