Abundances of disk and bulge giants from hi-res optical spectra: I. O,
  Mg, Ca, and Ti in the Solar neighborhood and Kepler field samples
  The galactic bulge is a significant part of our galaxy, but it is hard to
observe, being both distant and covered by dust in the disk. Therefore there do
not exist many hi-res optical spectra of bulge stars with large wavelength
coverage, whose determined abundances can be compared with nearby, similarly
analyzed stellar samples. We aim to determine the, for chemical evolution
models, so important alpha elements of a sample of bulge giants using hi-res
optical spectra with large wavelength coverage. The abundances found will be
compared to similarly derived abundances from similar spectra of similar stars
in the local thin and thick disks. In this first paper we focus on the Solar
neighborhood reference sample. We use spectral synthesis to derive the stellar
parameters as well as the elemental abundances of both the local as well as the
bulge samples of giants. Special care is taken to benchmark our method of
determining stellar parameters against independent measurements of effective
temperatures from angular diameter measurements and surface gravities from
asteroseismology. In this first paper we present the method used to determine
the stellar parameters as well as the elemental abundances, evaluate them, and
present the results for our local disk sample of 291 giants. When comparing our
determined spectroscopic temperatures to those derived from angular diameter
measurements, we reproduce these with a systematic difference of +10 K and a
standard deviation of 53 K. The spectroscopic gravities are reproducing the
ones determined from asteroseismology with a systematic offset of +0.10 dex and
a standard deviation of 0.12 dex. When it comes to the abundance trends, our
sample of local disk giants is closely following that of other works analyzing
solar neighborhood dwarfs, showing that the much brighter giant stars are as
good abundance probes as the often used dwarfs.
