An investigation of the multiple star Zeta Cnc by a lunar occultation

We analyze and discuss a lunar occultation of the multiple star ζ Cnc, obtained in the near-infrared. The longsought D component, recently imaged with the help of adaptive optics also by Hutchings et al. (2000), is clearly seen in the occultation light curve, and we determine its projected separation and brightness ratio with high accuracy. Regarding the suggested binary nature of D, we provide an estimate of the upper limit of its separation. In addition, we find evidence for a further component in the system. The signal from this latter is at the limit of detection, but it is confirmed by three independent data analysis methods. We discuss the astrometry and photometry of the system, and the implications for the mass and spectral characteristics of the components. With a projected separation of 0. ′′064, the proposed E component could form a close pair with ζ Cnc C. However, at the present stage we have to consider it only as tentative, and further observations by large telescopes or large interferometric facilities will be needed to confirm and study it in detail.