Journal Article

Surface inhomogeneities and line variability on DF Tau

Y. C. Unruh, A. Collier Cameron and E. Guenther

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 295, issue 4, pages 781-798
Published in print April 1998 | ISSN: 0035-8711
Published online April 1998 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1046/j.1365-8711.1998.01275.x
Surface inhomogeneities and line variability on DF Tau

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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.

Keywords: stars: imaging; stars: magnetic fields; stars: individual: DF Tau; stars: pre-main-sequence

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Subjects: Astronomy and Astrophysics

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