Mass loss in T tauri stars: observational studies of the cool parts of their stellar winds and expanding shells

Extensive high-resolution (Δν = 12 km s-1 FWHM) and high signal-to-noise ratio (S/N) line profile measurements of 25 T Tauri stars have been obtained using the Arizona/Smithsonian Multiple Mirror Telescope echelle spectrograph, and photon counting Reticon. In order to investigate the cooler regions of these stars, expanding envelopes, most of the profiles were of the Na D lines. Indications of mass loss in the Na D and Ca II H and K lines have been found in 11 stars. These stars show considerably stronger permitted and forbidden emission lines than the stars with negative detections. In eight of these 11 stars surprisingly narrow (10 km s-1< or = FWHM< or =50 km s-1), blueshifted absorptions were observed in the Na D lines, which were in some cases not variable in radial velocity over up to 2 years (Δν<3 km s-1). P Cygni profiles in the Na D lines with broad absorption components (100 km s-1< or =FWHM< or =250 km s-1) were observed in four stars