Astronomy and Astrophysics, volume 357, 951-956 (2000/5-3)
UV spectra of T Tauri stars from Hubble Space Telescope: RW Aur.
ERRICO L., LAMZIN S.A. and VITTONE A.A.
Abstract (from CDS):
Ultraviolet spectra of the classical T Tauri star RW Aur A observed with the Hubble Space Telescope were analysed. Absorption lines of neutral and singly ionized metals, blueshifted ∼50km/s relative to the star, were found. They originate in a dense (N>1010cm–3) gas outflow, whose extension along the line of sight is less than 3R*. The gas temperature of the wind is definitely below 10000K, but metals (and probably sulfur) are almost completely singly ionized by strong stellar emission in the hydrogen lines of the Lyman series. Stellar Lyα quanta are responsible for a significant population of hydrogen upper levels. Their photoionization is the main source of free electrons and subsequent gas heating. Strong fluorescent lines of H2 and FeII pumped by stellar Lyα quanta were found in the RW Aur spectra. The emission in CIV and SiIV lines is strongly suppressed by FeII and NiII wind absorption features. Superposition of strong H2 emission lines onto residual profiles additionally disturbs the picture, so CIV and SiIV line fluxes derived from low resolution IUE spectra are erroneous.