HD80606 b, a planet on an extremely elongated orbit

We report the detection of a planetary companion orbiting the solar-type st ar HD80606, the brighter component of a wide binary with a projected separa tion of about 2000 AU. Using high-signal spectroscopic observations of the two components of the visual binary, we show that they are nearly identical . The planet has an orbital period of 111.8 days and a minimum mass of 3.9 M-Jup. With e = 0.927, this planet has the highest orbital eccentricity amo ng the extrasolar planets detected so far. We finally list several processe s this extreme eccentricity could result from.