2008MNRAS.385..708S

We present Doppler imaging and Balmer line analysis of the weak-line T Tauri star TWA 6. Using these data we have made one of the first attempts to measure differential rotation in a T Tauri star, and the first detection of a slingshot prominence in such a star. We also show the most direct evidence to date of the existence of solar-type plages in a star other than the Sun.

Observations were made over six nights: 2006 February 11-13 and 2006 February 18-20, when spectra were taken with the UCL Echelle Spectrograph on the 3.9-m Anglo-Australian Telescope. Using least-squares deconvolution to improve the effective signal-to-noise ratio we produced two Doppler maps. These show similar features to maps of other rapidly rotating T Tauri stars, i.e. a polar spot with more spots extending out of it down to equator. Comparison of the two maps was carried out to measure the differential rotation. Cross-correlation and parameter fitting indicates that TWA 6 does not have detectable differential rotation.

The Balmer emission of the star was studied. The mean Hα profile has a narrow component consistent with rotational broadening and a broad component extending out to ±250km/s. The variability in Hα suggests that the chromosphere has active regions that are cospatial with the spots in the photosphere, similar to the `plages' observed on the Sun. In addition the star has at least one slingshot prominence 3R_*above the surface - the first such detection in a T Tauri star.