The binary nature of this system was announced in 1980 by
Erika Böhm-Vitense based on an
ultraviolet excess attributed to a
white dwarf companion. It is a single-lined
spectroscopic binary system with an
orbital period of and an
eccentricity (ovalness) is 0.25. It was flagged as a suspected
eclipsing binary in 1988 due to observed variations in the
light curve. The primary, designated component A, has a
stellar classification of G4Ib: Ba2. This notation indicates this is a yellow-hued
supergiant star, although the ':' means there is some uncertainty about the class. The temperature and surface gravity of this object suggest it may be a
horizontal-branch star. It is considered a prototypical example of a
Barium star, as indicated by the 'Ba2' class suffix. The properties of these objects include overabundances of carbon molecules (such as C2) and
s-process elements. Zeta Capricorni has an overabundance of the s-process element
praseodymium. Its companion, component B, is a carbon-oxygen
white dwarf with a
hydrogen-rich atmosphere and a class of DA2.2. It is about two-thirds as massive as the
Sun, and its temperature is . In the course of its evolution, the progenitor star passed through the thermally pulsing
asymptotic giant branch, during which the enlarged atmosphere transferred material to the primary. The abundance of
niobium in the primary's atmosphere, a product of the decay of
zirconium-93, is at a level that suggests the transfer to the primary took place more than three million years ago. A magnitude 12.5
visual companion was discovered by
T. J. J. See in 1897. As of 1997, it was located at an
angular separation of along a
position angle of 12°. ==Chinese name==