Magnetospheric accretion and winds on the T Tauri star SU Aurigae - Multi-spectral line variability and cross-correlation analysis

SU Aurigae is a T Tauri star that was well monitored during the MUSICOS 96 multi-site campaign. We present the results of the spectroscopic analysis o f the circumstellar environment of this star, particularly of the H alpha, H beta, Na I D and He I D3 line profiles. The signatures of modulated outfl ows and mass accretion events are analysed, as well as transient spectral f eatures. We compute the cross-correlation function (CCF) of several pairs o f (velocity bins in) spectral lines to better investigate the profiles' tem poral variability. We found increasing time lags between the variability of He I D3, Na I D and H beta. We propose this may be understood in terms of azimuthal distortion of the magnetic field lines due to the different rotat ion rates of the star and the disk. We find the slightly blueshifted absorp tion features in H alpha, H beta and Na I D to be anti-correlated with the accretion flow signatures, We propose that the transient absorption feature s in the blue wings of H alpha, H beta and Na I D (signatures of mass outfl ows), and flare brightenings are related to the disruption of distorted mag netospheric field lines.