NEAR-INFRARED OBSERVATIONS OF YOUNG STELLAR OBJECTS IN THE RHO-OPHIUCHI DARK CLOUD

We have conducted an imaging survey of 1.4 pc2 (650 arcmin2) of the rho-Ophiuchi dark cloud in the J, H, and K near-infrared photometric bands. Approximately 337 of our 481 detected sources are associated with the cloud, and we estimate that 48% of these have near-infrared excesses, indicative of disks or circumstellar material surrounding these young stellar objects (YSOs). The K-band luminosity function is significantly different in different regions of our survey area, suggesting that YSOs in these regions have different ages or mass functions. We estimate that the entire survey area has a high star-formation efficiency, SFE almost-equal-to 23%. Finally, our many newly detected sources provide a relatively large, uniformly sensitive sample of objects for study at longer wavelengths to better determine true source luminosities and evolutionary lifetimes.