High Accuracy Radial Velocity Planet Searcher
One team, led by Francesco Pepe, used the High Accuracy Radial Velocity Planet Searcher-North (HARPS-N) spectrograph at the Telescopio Nazionale Galileo in the Canary Islands to estimate that the planet has a mass 1.86 times that of the Earth and a radius 1.16 times greater. The other, led by Andrew Howard of the University of Hawaii at Manoa, used data from the High Resolution Eschelle Spectrometer on the Keck 1 Telescope at the W.M. Keck Observatory in Hawaii to estimate the mass as 1.69 times that of the Earth and the radius as 1.12 times larger. Both estimates put the planet's density at about 5.5 grams per cubic centimetre, which is equivalent to that of the Earth and possibly indicative of a rock-iron composition like Earth's. The iron core could build up to 40% of the planet mass.