We present new precise HIRES radial velocity ( RV ) data sets of five nearby stars obtained at Keck Observatory .
HD 31253 , HD 218566 , HD 177830 , HD 99492 and HD 74156 are host stars of spectral classes F through K and show radial velocity variations consistent with new or additional planetary companions in Keplerian motion .
The orbital parameters of the candidate planets in the five planetary systems span minimum masses of \mathcal { M } \sin i = 27.43 \mathcal { M } _ { \earth } to 8.28 \mathcal { M } _ { J } , periods of 17.05 to 4696.95 days and eccentricities ranging from circular to extremely eccentric ( e \approx 0.63 ) .

The 5th star , HD 74156 , was known to have both a 52-day and a 2500-day planet , and was claimed to also harbor a 3rd planet at 336d , in apparent support of the “ Packed Planetary System ” hypothesis .
Our greatly expanded data set for HD 74156 provides strong confirmation of both the 52-day and 2500-d planets , but strongly contradicts the existence of a 336-day planet , and offers no significant evidence for any other planets in the system .