The circumstellar environment of chromospherically active T Tauri stars.

The authors discuss new spectroscopic material on 7 T Tauri stars of low intermediate activity level which have envelopes of low optical thickness and small circumstellar/interstellar extinction. They show that difference plots between the target star and appropriate standards are a powerful tool to probe the stellar envelope structure. In this sample the authors find 1 object with a P Cyg type, 3 with inverse P Cyg type, and 3 with symmetrical Balmer line profiles. They conclude that the physical processes in these T Tauri stars do not differ qualitatively from the ones found in extremely active ones. In particular, the inverse P Cyg type profiles are not restricted to stars with very opaque envelopes and are possibly a much more common attribute of young stellar objects.