Surface inhomogeneities and line variability on DF Tau |
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| Authors: | Y C Unruh A Collier Cameron & E Guenther |
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| Institution: | School of Physics &Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS,;Department of Physics, Queen Mary &Westfield College, Mile End Road, London E1 4NS,;Thüringer Landessternwarte Tautenburg, Karl-Schwarzschild-Observatorium, D-07778 Tautenburg, Germany |
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| Abstract: | We have mapped surface inhomogeneities on the classical T Tauri star DF Tau, using the Li i doublet at 670.8 nm, the Ca i lines at 612.2 nm and 643.9 nm and a calcium and iron blend at 646.3 nm. We find compelling evidence that there are hotspots with temperatures of more than 5000 K. Two of the hotspots produce line-profile deformations that can be traced as they move through the cross-correlated profiles. When one of the hotspots crosses the stellar disc, redshifted absorption components appear in the Na D lines. As these redshifted absorption features are usually tracers for mass-infall we interpret this hotspot as an accretion shock close to the stellar surface. Parts of the surface of DF Tau are covered with a hot chromosphere that is visible in the Ca ii infrared triplet lines and the narrow component of He i . We find no correlation between the veiling and the lines that originate from the hot chromosphere, suggesting that the veiling and the chromospheric emission are produced in physically distinct regions. |
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| Keywords: | stars: imaging stars: magnetic fields stars: individual: DF Tau stars: pre-main-sequence |
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