Cold DUst around NEarby Stars (DUNES). First results

We present the first far-IR observations of the solar-type stars <i>δ<i/> Pav, HR 8501, 51 Peg and <i>ζ<i/><sup>2<sup/> Ret, taken within the context of the DUNES <i>Herschel<i/> open time key programme (OTKP). This project uses the PACS and SPIRE instruments with the objective of studying infrared excesses due to exo-Kuiper belts around nearby solar-type stars. The observed 100 <i>μ<i/>m fluxes from <i>δ<i/> Pav, HR 8501, and 51 Peg agree with the predicted photospheric fluxes, excluding debris disks brighter than <i>L<i/><sub>dust<sub/>/ ~ 5 × 10<sup>-7<sup/> (1<i>σ<i/> level) around those stars. A flattened, disk-like structure with a semi-major axis of ~100 AU in size is detected around <i>ζ<i/><sup>2<sup/> Ret. The resolved structure suggests the presence of an eccentric dust ring, which we interpret as an exo-Kuiper belt with <i>L<i/><sub>dust<sub/>/ <i>≈<i/> 10<sup>-5<sup/>.