  This paper extends our previous study of planet/brown dwarf accretion by
giant stars to solar mass stars located on the red giant branch. The model
assumes that the planet is dissipated at the bottom of the convective envelope
of the giant star. The giant's evolution is then followed in detail. We analyze
the effects of different accretion rates and different initial conditions. The
computations indicate that the accretion process is accompanied by a
substantial expansion of the star, and in the case of high accretion rates, hot
bottom burning can be activated. The possible observational signatures that
accompany the engulfing of a planet are also extensively investigated. They
include : the ejection of a shell and a subsequent phase of IR emission, an
increase in the 7Li surface abundance and a potential stellar metallicity
enrichment, spin-up of the star due to the deposition of orbital angular
momentum, the possible generation of magnetic fields and a related X-ray
activity due to the development of shear at the base of the convective
envelope, and the effects on the morphology of the horizontal branch in
globular clusters. We propose that the IR excess and high Li abundance observed
in 4-8% of the G and K giants originate from the accretion of a giant planet, a
brown dwarf or a very low-mass star.
