Symbiotic binary

They are also vital in the study of stellar wind, ionized nebulae, and accretion because of the unique interstellar dynamics present within the system.

More commonly it is considered as the prototype of only a subset of symbiotic stars with irregular variations up to about 4 magnitudes in amplitude.

They appear similar to classical novae but have extremely slow outbursts that can remain near maximum brightness for years.

[1] The typical behavior of symbiotic binaries can be divided into two phases, based on the rate of accretion to the compact component.

They were first recognized as a class of stars with unique spectroscopic qualities by Annie Cannon near the beginning of the 20th century.

Their binary nature was made clear by the simultaneous existence of the spectral lines indicative of a red giant and of a white dwarf or neutron star.

[5] D-type systems are surrounded by optically thick dusty nebulosity and the star itself is not directly visible.