T Tauri Stars observed with I.U.E. Catalogue
T Tauri Stars (TTS) are low mass (M≤ 1M⊙) pre-main sequence (PMS) stars. They are often classified into two main sub-classes: classical TTS (cTTS) and weak line TTS (wTTS). This classification is based on the strength of the Hα line (W(Hα ) ≥ 10 Å for cTTS and W(Hα ) ≤ 10 Å for wTTS) that was taken primitively as a good tracer of their magnetic activity (and youth).
Herbig-Haro Objects Observed with I.U.E Catalogue
Herbig-Haro Objects (HHOs) are shock-excited nebulosities observed in star forming regions. They are powered by the energy released in the shocks between outflows from pre-main-sequence stars and interstellar gas (or previous ejecta)