We report precision Doppler measurements of three intermediate–mass subgiants obtained at Lick and Keck Observatories .
All three stars show variability in their radial velocities consistent with planet–mass companions in Keplerian orbits .
We find a planet with a minimum mass M _ { P } \sin { i } = 2.5 M _ { Jup } in a 351.5 day orbit around HD 192699 , a planet with a minimum mass of 2.0 M _ { Jup } in a 341.1 day orbit around HD 210702 , and a planet with a minimum mass of 0.61 M _ { Jup } in a 297.3 day orbit around HD 175541 .
Mass estimates from stellar interior models indicate that all three stars were formerly A–type , main–sequence dwarfs with masses ranging from 1.65 M _ { \odot } to 1.85 M _ { \odot } .
These three long–period planets would not have been detectable during their stars ’ main–sequence phases due to the large rotational velocities and stellar jitter exhibited by early–type dwarfs .
There are now 9 “ retired ” ( evolved ) A–type stars ( M _ { * } > 1.6 M _ { \odot } ) with known planets .
All 9 planets orbit at distances a \geq 0.78 AU , which is significantly different than the semimajor axis distribution of planets around lower–mass stars .
We examine the possibility that the observed lack of short–period planets is due to engulfment by their expanding host stars , but we find that this explanation is inadequate given the relatively small stellar radii of K giants ( R _ { * } < 32 R _ { \odot } = 0.15 AU ) and subgiants ( R _ { * } < 7 R _ { \odot } = 0.03 AU ) .
Instead , we conclude that planets around intermediate–mass stars reside preferentially beyond \sim 0.8 AU , which may be a reflection of different formation and migration histories of planets around A–type stars .