Infrared photometry of low-mass stars in Praesepe

We present follow-up infrared photometry for a sample of low-mass and very low-mass stars in the Praesepe open cluster. Our sample is selected from tw o sources: (i) 90 stars selected from the Hambly et al. photometric and pro per-motion survey of Praesepe; (ii) 17 stars selected from the CCD imaging survey presented by Pinfield et al. We investigate cluster membership using infrared colour-magnitude and colour-colour diagrams. We find 81 likely an d two possible members in the Hambly et al. sample, in line with prediction s. Contamination in the Pinfield et al. sample is higher, and we find nine probable cluster members. We investigate the non-grey models of Baraffe et al., which are found to be in good agreement with the data. Multiplicity in Praesepe is also examined, and we find the multiple star fraction to be 0. 51 from analysis of the I, I-K diagram. We investigate individual object ma sses, and find that the faintest candidate cluster members have masses clos e to the substellar limit.