Vol. 567
In section 7. Stellar structure and evolution

Dynamical star-disk interaction in the young stellar system V354 Monocerotis

by N.N.J. Fonseca, S.H.P. Alencar, J. Bouvier, et al. A&A 567, A39


The light curve of the classical T Tauri star V354 Mon shows periodical minima that vary in depth and width at each rotational cycle. The photometric observations carried out by the authors indicate that the system becomes slightly bluer as the flux increases. The spectra obtained by the authors exhibit variable emission lines, with redshifted absorption components associated with a disk wind and blueshifted ones with the accretion process, which confirms the magnetospheric accretion scenario. From the analysis of the photometric and spectroscopic data, the authors identify correlations between the emission line variability and the light-curve modulation of the young system, such as the occurrence of pronounced redshifted absorption in the Hα line at the epoch of minimum flux. The authors find that the accretion funnel is seen projected onto the stellar photosphere along the line of sight, which implies that the hot spot coincides with the light-curve minima. They conclude that material non-uniformly distributed in the inner part of the circumstellar disk is the main cause of the photometric modulation, but do not exclude that there might be hot and cold spots at the stellar surface. The distortion in the inner part of the disk is thought to be created by the dynamical interaction between the stellar magnetosphere and the circumstellar disk, as also observed in the T Tauri star AA Tau and predicted by magneto-hydrodynamical numerical simulations.