Young stellar objects are surrounded by a circumstellar disk, from which material is falling onto the stellar surface. According to the magnetospheric accretion model, the stellar magnetic field truncates the disk at the distance of a few stellar radii and channels the disk material onto the star. Although usually described with simple and static models, this accretion process is inherently time variable, therefore our aim is to characterize the accretion process in time and study the accretion diagnostic parameters. Here, we present a complex study of VW Cha, a low-mass young star. We combined the TESS observations with contemporaneous ground-based IJHK-band photometry, and multi-epoch optical spectroscopic observations obtained by the VLT/ESPRESSO and the 2.2m/FEROS spectrographs. Besides uncovering the periodic light variations that can be attributed to the stellar rotation, the uninterrupted TESS observations allow us to examine the shorter timescale fluctuations probably due to accretion variability. Using the additional observations, we identify accretion tracers and study where they form, measure the accretion rate, and determine the distribution and the kinematics of the accreting material.
This project has reveived funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agrement No 716155).