Knowledge of the evolution of circumstellar accretion disks is pivotal to our understanding of star and planet formation; and yet despite intensive theoretical and observational studies, the disk dissipation process is not well understood. Infrared observations of large numbers of young stars, as performed by the Spitzer Space Telescope, may advance our knowledge of this inherently complex process. While infrared data reveal the evolutionary status of the disk, they hold little information on the properties of the central star and the accretion characteristics. Existing 2MASS and Spitzer archive data of the Lynds 1630N and 1641 clouds in the Orion GMC provide disk properties of a large number of young stars. We wish to complement these data with optical data that provide the physical stellar parameters and accretion characteristics.

Cone search capability for table J/A+A/504/461/table16 (Photometric magnitudes for transition disk object candidates)

Cone search capability for table J/A+A/504/461/EWs (Equivalent widths of emission lines of the optical spectra for YSOs)

Cone search capability for table J/A+A/504/461/YSOs (Parameters and photometry of the YSOs studied in L1630N and L1641)