Infrared observations of young stars - VII. Simultaneous optical and infrared monitoring for variability.
The results of simultaneous photoelectric photometry at U, B, V, R, I and Ma in the optical, and 2, 3, 5, 8, 10 and I I in the infrared are reported for a number of young stars. Of 22 T Tauri and T Tauri-related early-type variables observed, 13 exhibited significant variations on a one-day time scale. The largest amplitude variations occurred in RW Aur for which changes at all wavelengths were correlated in time, and for DK Tau for which changes in the optical continuum fluxes were anti-correlated with the infrared and Hcc changes. Complex and often erratic behaviour is noted in most of the stars, suggesting the presence of multiple emission components.