Radial velocity curve of {delta} Cir

Penny et al. discovered the presence of a third component in the IUE spectra. The eclipsing binary and the third body revolve around a common center of gravity with a period of 1644days in an eccentric orbit with a semimajor axis of 10AU.

We demonstrate the presence of apsidal-line rotation with a period of {approx}141yr, which is considerably longer than its theoretically predicted value, based on the published radii of the binary components derived from the Hipparchos H_p_ light curve. However, our new solution of the same light curve resulted in smaller radii and better agreement between the observed and predicted period of the apsidal-line advance. There are indications that the third body is a binary.