symbiotic star(sim-bÿ-ot -ik, -bee-) A variable ‘star’ whose spectrum shows lines characteristic of gases at two very different temperatures, typically of an M star (3500 K) and a B star (20 000 K) superimposed. It is in fact a semidetached close binary star: a red giant component produces the low-temperature spectrum whereas the higher-temperature spectrum comes from gas streams that are falling on to a companion star, usually a white dwarf or a main-sequence star, but sometimes possibly a neutron star. The mass loss is due to the giant's stellar wind, and so is much slower than the gravitational transfer in the otherwise-similar recurrent novae. Symbiotic stars suffer smaller and more irregular outbursts than other cataclysmic variables. An outburst in the R Aquarii system has produced a narrow jet some 1500 AU in length, visible to optical and radio telescopes. The gas in the jet is traveling at 2000 km s–1, and is apparently a milder version of the ejection found in SS433. Some other well-studied symbiotic stars are Z Andromedae, BF Cygni, RW Hydrae, AG Pegasi, and AX Persei.
symbiotic star[‚sim·bē′äd·ik ′stär]
A stellar object whose optical spectrum displays features indicative of two very different stellar regimes: a stellar spectrum whose flux distribution and absorption lines suggest the presence of a cool star, and emission lines which can be formed only in a much hotter medium.