Toruń Centre for Astronomy
Nicolaus Copernicus University

On the nature of the symbiotic binary CI Cygni

Kenyon S. J., Oliversen N. A., Mikolajewska J., Mikolajewski M., Stencel R. E., Garcia M. R., Anderson C. M.
1991

An analysis of ultraviolet and optical spectroscopy is presented for the symbiotic binary CI Cyg. This system contains an M5 II asymptotic branch giant Mg of about 1.5 solar mass, transfering material at a few times 0.00001 solar mass/yr into a large accretion disk surrounding a main-sequence star with Mh of about 0.5 solar mass. A boundary layer at the inner edge of the disk photoionizes a small nebula approximately confined to the Roche volume of the accreting star. An extended, more highly ionized region forms when material ejected from the disk interacts with the red giant wind.

Keywords
Accretion Disks, Asymptotic Giant Branch Stars, Binary Stars, Main Sequence Stars, Symbiotic Stars, Absorption Spectra, Emission Spectra, Interstellar Extinction, Nebulae, Stellar Mass Accretion, Stellar Spectrophotometry, Stellar Winds