Symbiotic stars are known as binary systems with both cool and hot components with enshrounding nebulous gas. The cool component, M-type giant, is presumably loosing its mass into a hot white or main sequence companion star through the inner Lagrangian point. The lines emit from the ionized nebulous region around the hot star while the mass loss or accretion activity is believed to be the main cause of sudden variation of the continuum and line fluxes. We selected 17 symbiotics for which the emission line fluxes were measured from the IUE SWP, LWR data, to find variability of spectrum. We also investigated the periodic variation of emissions or eclipsing effect from the IUE lines. All of our symbiotics show very high electron densities in the emission regions. For other optical symbiotics, the observations had been carried in 1999 with BOAO mid-resolution spectrometer. We classified symbiotics based on their outburst activities, or emission line characteristics, i.e., OVIλ6830.TheOVIλ6830 OVIλ6830.TheOVIλ6830 emission lines are also found in S-type symbiotics, which have been known as charateristics of D-types.

• 김여정(충남대학교 천문우주과학과) | KIM YEOJEONG (Dept. of Astronomy and Space Science, Chungnam National University)
• 형식(한국천문연구원 보현산 천문대) | HYUNG SIEK (Korea Astronomy Observatory)
• LAWRENCE H. ALLER(Dept. of Physics and Astronomy, UCLA)