  Recent surveys have revealed a lack of close-in planets around evolved stars
more massive than 1.2 Msun. Such planets are common around solar-mass stars. We
have calculated the orbital evolution of planets around stars with a range of
initial masses, and have shown how planetary orbits are affected by the
evolution of the stars all the way to the tip of the Red Giant Branch (RGB). We
find that tidal interaction can lead to the engulfment of close-in planets by
evolved stars. The engulfment is more efficient for more-massive planets and
less-massive stars. These results may explain the observed semi-major axis
distribution of planets around evolved stars with masses larger than 1.5 Msun.
  Our results also suggest that massive planets may form more efficiently
around intermediate-mass stars.
