We report the detection of eighteen Jovian planets discovered as part of our Doppler survey of subgiant stars at Keck Observatory , with follow-up Doppler and photometric observations made at McDonald and Fairborn Observatories , respectively .
The host stars have masses 0.927 \leq M _ { \star } / M _ { \odot } \leq 1.95 , radii 2.5 \leq R _ { \star } / R _ { \odot } \leq 8.7 , and metallicities -0.46 \leq [ Fe/H ] \leq + 0.30 .
The planets have minimum masses 0.9 M _ { Jup } \leq M _ { P } \sin i~ { } \lesssim 13 M _ { Jup } and semimajor axes a \geq 0.76 AU .
These detections represent a 50 % increase in the number of planets known to orbit stars more massive than 1.5 M _ { \odot } and provide valuable additional information about the properties of planets around stars more massive than the Sun .