Characteristic times of wind variability in classical T Tauri stars

Abstract

Results of observations of short-term wind variability in the classical T Tauri stars RW Aur and DR Tau are presented. Since the H CaII emission is absorbed by the absorption component of the H∈ line, which arises in the wind at a radial velocity of about −120 km/s, the ratio of equivalent widths of the H and K emission lines of ionized calcium is used as an indicator of the line-of-sight wind density. Observations showed that the wind densities of RW Aur and DR Tau vary with a characteristic time of 4 to 5 days, i.e., with a period that is somewhat shorter than the period of the axial rotation of these stars. These results are interpreted in the framework of the conical wind model, which predicts cyclic repetitions of accretion and ejection events caused by the interaction of the star’s magnetosphere with the ionized gas at the inner boundary of the accretion disc.