New high and low resolution IUE spectra of AG Dra, obtained when the star was still in its active phase, are analyzed and interpreted. The spectra are characterized by strong permitted and weak intercombination emission lines belonging to a wide ionization range, from O I, Mg II, to He II, O V, S V, superimposed on an intense continuum. Several strong lines are identified as derived from the 2200 A interstellar band. All the emission lines are shifted by -115 km/s with respect to the interstellar lines. He II 1640 has extended wings probably not produced by Thomson scattering. The N V resonance double displays a P Cygni profile with an absorption minus emission velocity separation of 120 km/s, which seems to arise in a warm wind. Two possible explanations of this warm wind are discussed. A hot continuum shortwards of 1600 A and a flatter continuum at longer wavelengths are identified in the UV continuum. Energy balance considerations lead to the conclusion that AG Dra is a binary system.
Viotti, R., Ricciardi, O., Ponz, D., Giangrande, A., Friedjung, M., Cassatella, A., et al. (1983). IUE observations of the high velocity symbiotic star AG Draconis during active phase. ASTRONOMY & ASTROPHYSICS, 119, 285-293.
IUE observations of the high velocity symbiotic star AG Draconis during active phase
ALTAMORE, Aldo
1983-01-01
Abstract
New high and low resolution IUE spectra of AG Dra, obtained when the star was still in its active phase, are analyzed and interpreted. The spectra are characterized by strong permitted and weak intercombination emission lines belonging to a wide ionization range, from O I, Mg II, to He II, O V, S V, superimposed on an intense continuum. Several strong lines are identified as derived from the 2200 A interstellar band. All the emission lines are shifted by -115 km/s with respect to the interstellar lines. He II 1640 has extended wings probably not produced by Thomson scattering. The N V resonance double displays a P Cygni profile with an absorption minus emission velocity separation of 120 km/s, which seems to arise in a warm wind. Two possible explanations of this warm wind are discussed. A hot continuum shortwards of 1600 A and a flatter continuum at longer wavelengths are identified in the UV continuum. Energy balance considerations lead to the conclusion that AG Dra is a binary system.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
