The HARPS survey for southern extra-solar planets II. A 14 Earth-masses   exoplanet around mu Arae
  In this letter we present the discovery of a very light planetary companion to the star mu Ara (HD160691). The planet orbits its host once every 9.5days, and induces a sinusoidal radial velocity signal with a semi-amplitude of 4.1 m/s, the smallest Doppler amplitude detected so far. These values imply a mass of m2 sini = 14 earth-masses. This detection represents the discovery of a planet with a mass slightly smaller than that of Uranus, the smallest ``ice giant" in our Solar System. Whether this planet can be considered an ice giant or a super-earth planet is discussed in the context of the core-accretion and migration models. 
N.C. Santos, F. Bouchy, M.Mayor, F. Pepe, D. Queloz, S. Udry, C.   Lovis, M. Bazot, W. Benz, J.-L. Bertaux, G. Lo Curto, X. ...