Forbidden line and H-alpha profiles in T Tauri star spectra - A probe of anisotropic mass outflows and circumstellar disks

The authors report the results of a high-resolution spectroscopic study of 10 T Tauri stars (TTS) and two Herbig emission stars. Red echelle spectra include the lines of [O I] λ6300, [N II] λ6584, [S II] λλ6716, 6731, as well as Hα. The forbidden lines display a continuous progression of profile types, from single-peaked profiles with maxima near the stellar rest velocity and broad (150 km s<SUP>-1</SUP>) blue wings, to double-peaked profiles with blueshifted maxima displaced by as much as 200 km s<SUP>-1</SUP> from the second peak near the stellar rest velocity. It is found that the observed range of profile types is best explained by a wind with a latitude dependent velocity field, such that the wind velocity is higher at the poles than at the equator. The authors also present estimates of the average densities (10<SUP>4</SUP>cm<SUP>-3</SUP>), sizes (tens of AU) for the TTS forbidden emission regions, and compute mass-loss rates (10<SUP>-7</SUP> to 10<SUP>-9</SUP>M_sun;yr<SUP>-1</SUP>). The absence of redshifted forbidden line emission demands that the receding part of the mass ouflows must be obscured; an optically opaque circumstellar disk seems a logical candidate for such a screen. IRAS far-infrared fluxes are used to estimate the disk sizes on the assumption that they are optically thick at 100 μm. The implied masses of these circumstellar disks range from 0.01 to 0.1 M_sun;.