Circumstellar Disk Candidates Identified in NGC 2264

Abstract

We present an optical and near-infrared study of a 45 0 Â 45 0 field in NGC 2264, which includes both S Mon and the Cone Nebula. We report photometry at optical (UBVR C I C) and near-infrared (JHK) wave-lengths for $5600 stars and spectroscopic classifications for $400 of these stars. We identify circumstellar disk candidates using three techniques: excess ultraviolet (UÀV) emission, excess near-IR (IÀK and HÀK) emission, and H emission-line equivalent widths for those stars with spectra. We find generally good corre-lation between disk indicators thought to originate from different physical processes. We find little if any evo-lution of disk fraction with stellar age or mass. However, when we derive mass accretion rates (_ M M) from the excess emission at U, we find that _ M M decreases with age over the age range spanned by our data, $0.1–5 Myr, and increases with mass over the range $0.25–1 M . These findings are comparable to results found previ-ously by us in the Orion Nebula cluster flanking fields.