  The metal content of planet hosting stars is an important ingredient which
may affect the formation and evolution of planetary systems. Accurate stellar
abundances require the determinations of reliable physical parameters, namely
the effective temperature, surface gravity, microturbulent velocity, and
metallicity. This work presents the homogeneous derivation of such parameters
for a large sample of stars hosting planets (N=117), as well as a control
sample of disk stars not known to harbor giant, closely orbiting planets
(N=145). Stellar parameters and iron abundances are derived from an automated
analysis technique developed for this work. As previously found in the
literature, the results in this study indicate that the metallicity
distribution of planet hosting stars is more metal-rich by ~0.15 dex when
compared to the control sample stars. A segregation of the sample according to
planet mass indicates that the metallicity distribution of stars hosting only
Neptunian-mass planets (with no Jovian-mass planets) tends to be more
metal-poor in comparison with that obtained for stars hosting a closely
orbiting Jovian planet. The significance of this difference in metallicity
arises from a homogeneous analysis of samples of FGK dwarfs which do not
include the cooler and more problematic M dwarfs. This result would indicate
that there is a possible link between planet mass and metallicity such that
metallicity plays a role in setting the mass of the most massive planet.
Further confirmation, however, must await larger samples.
