Line-profiles of the high-ionization-potential ions and the nature of the emission-line regions of the t-tauri-type stars

Abstract

Using the archival spectrograms, obtained by IUE in 1980s, the line profiles of the CIII, CIV, SiIII, SiIV ions were studied in the spectra of four T Tau-type stars: RU Lup, T Tau, TW Hya, and DR Tau. The lines, reliably detected above the noise level, have asymmetric profiles, redshifted with respect to the laboratory wavelengths. This peculiarity of the profiles can be explained in the case of disk accretion onto a young star, when the star's global magnetic field stops the accretion disk at some distance from the stellar surface.