Circumstellar disk candidates identified in NGC 2264

We present an optical and near-infrared study of a 45' x 45' field in NGC 2264, which includes both S Mon and the Cone Nebula. We report photometry at optical (UBVRCIC) and near-infrared (JHK) wavelengths for similar to5600 stars and spectroscopic classifications for similar to400 of these stars. We identify circumstellar disk candidates using three techniques: excess ultraviolet ( U V) emission, excess near-IR (I-K and H-K) emission, and Halpha emission-line equivalent widths for those stars with spectra. We find generally good correlation between disk indicators thought to originate from different physical processes. We find little if any evolution of disk fraction with stellar age or mass. However, when we derive mass accretion rates ((M)over dot) from the excess emission at U, we find that (M)over dot decreases with age over the age range spanned by our data, similar to0.1-5 Myr, and increases with mass over the range similar to0.25-1 M-circle dot. These findings are comparable to results found previously by us in the Orion Nebula cluster flanking fields.