We have discovered variable He I absorption lines with red-shifts of about 100 km s-1 in the T Tauri star BM Andromedae. The presence of He I is quite unexpected, since BM And has a largely unveiled G8V spectrum, moderate Hα emission (E.W. of 8-25 Å), and a normal UV-excess. The higher Balmer lines show inverse p Cygni Balmer profiles whenever He I is in absorption and have the same absorption line velocities. All of these lines come and go during our observations without any sign of significant velocity changes. We interpret these features as the result of very hot material falling onto the star at a rate of at least 1O-9 Msun yr-1. We have also seen this direct indication of accretion in a few other WTTSs whose properties are quite close to those of BM And.
Astronomy and Astrophysics
- Pub Date:
- September 1993
- Stars: pre-main-sequence - Stars: T Tauri - Stars: variable - Stars: emission-line - Stars: BM And