Search for far-infrared variability of protoplanetary disks in the Cha I star-forming region

The research of star formation is one of the most popular area of modern astrophysics. Nowadays, we can use ground-based and space-borne observatories to study Young Stellar Objects in different states of their evolution, their time-domain behaviour related to accretion process, and the connection between the stars and their circumstellar environment. The Chamaeleon I molecular cloud complex is one of the most famous star-forming regions, located at a distance of 190 pc. In our study we use photometric data to analyse the multi-wavelength variability of eight T Tauri stars (CR Cha, CT Cha, Glass I, VW Cha, VZ Cha, WW Cha, WX Cha and XX Cha) in Cha I. Our aim is to determine the disk’s thermal response on changing irradiation by the central source, with special emphasis on the little known far-infrared flux variations of the outer disk. For our analysis, we performed a 4-epoch weekly monitoring of the 8 stars using the CTIO 1.3m optical – near-IR telescope, the VLT/ISAAC L- and M-band camera, and the Herschel Space Observatory at 70 and 160 micrometer. We looked for far-infrared flux changes and their correlation with the simultaneous variation of the stellar luminosity. Here, we present the first results, and perform a simply analytical modeling of the expected far-infrared variability using a two-layer disk model. The project provides some first hints on how the stellar radiation influences the large outer regions of the circumstellar disk.