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Magnetospheric accretion and winds on the T Tauri star SU Aurigae
Multi-spectral line variability and cross-correlation analysis *
J.M. Oliveira 1,2,
B.H. Foing 1,3,
J.Th. van Loon 4 and
Y.C. Unruh 5
Received 12 May 2000 / Accepted 21 August 2000
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 of the circumstellar environment of this star, particularly of the H, H, NaI D and HeI D3 line profiles. The signatures of modulated outflows and mass accretion events are analysed, as well as transient spectral features. We compute the cross-correlation function (CCF) of several pairs of (velocity bins in) spectral lines to better investigate the profiles' temporal variability. We found increasing time lags between the variability of HeI D3, NaI D and H. We propose this may be understood in terms of azimuthal distortion of the magnetic field lines due to the different rotation rates of the star and the disk. We find the slightly blueshifted absorption features in H, H and NaI D to be anti-correlated with the accretion flow signatures. We propose that the transient absorption features in the blue wings of H, H and NaI D (signatures of mass outflows), and flare brightenings are related to the disruption of distorted magnetospheric field lines.
Key words: stars: pre-main sequence stars: circumstellar matter line: profiles stars: activity stars: magnetic fields stars: individual: SU Aur
* Based on observations obtained during the MUSICOS 96 campaign in which were involved: Isaac Newton Telescope (INT, La Palma), Observatoire de Haute Provence (OHP, France), McDonald Observatory (MDO, USA), Beijing Astronomical Observatory (BAO, Xinglong, China) and Canada-France-Hawaii Telescope (CFHT, Hawaii).
Send offprint requests to: J.M. Oliveira (email@example.com)
Online publication: October 24, 2000