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We report optical spectroscopic and photometric results from our long-term study of the T Tauri star WY Arietis (LkH 264). The data gathered show dierent types of variability: variations in the continuum level, in the emission line fluxes and line proles. The timescales associated with these variations appear quite diverse. The correlation found between the variations observed in the veiling and in the continuum flux strongly suggest that an extra continuum source veiling the stellar photospheric spectrum is the cause driving the continuum variability. The present work also unveils the presence of an accretion flow onto the star, as revealed by the O I 7773 Aa nd8446 A line proles, which is the rst unambiguous model-independent detection of such an event in this star. Our photometric data allowed us to nd a period of 3.04 days for this star, somewhat in tune with Fernandez & Eiroa (1996). However, due to the poor time sampling our nding should be taken as tentative. A detailed analysis of the broad and narrow components of the He I line proles indicates the presence of a hot wind during the November 1993 observation while in October 1999 a wind is only revealed by the blue wing asymmetry of the observed Balmer and CaII infrared triplet line proles. The correlation between the strength of the hot wind and the amount of flux in the emission lines led also to the conclusion that this type of wind provides a signicant contribution to the hydrogen and metal emission lines. We have also witnessed an exceptional activity during one of the nights which may be attributed to an increase in LkH 264's accretion rate or to a flare-like event. Although it is not possible to clearly distinguish between these possibilities, the available data set points towards variable accretion as being responsible for the observed event.

On the nature of variations in the T Tauri star WY Arietis (LkHα264)