Spectroscopy of Dwarf Stars Around the North Celestial Pole
  New space missions (e.g., NASA-TESS and ESA-PLATO) will perform an analysis
of bright stars in large fields of the celestial sphere searching for
extraterrestrial planets. Asteroseismic observations will search for
exoplanet-hosting stars with solar-like oscillations. In order to achieve all
the goals, a full characterization of the stellar objects is important.
However, accurate atmospheric parameters are available for less than 30% of
bright dwarf stars of the solar neighborhood. In this study we observed
high-resolution (R = 60,000) spectra for all bright (V < 8 mag) and cooler than
F5 spectral class dwarf stars in the northern-most field of the celestial
sphere with radius of 20{\deg} from the {\alpha}(2000) = 161$^\circ$03 and
{\delta}(2000) = 86$^\circ$60 that is a center of one of the preliminary
ESO-PLATO fields. Spectroscopic atmospheric parameters were determined for 140
slowly rotating stars, for 73% of them for the first time. The majority (83%)
of the investigated stars are in the TESS object lists and all of them are in
the preliminary PLATO field. Our results have no systematic differences when
compared with other recent studies. Comparing our results for 39 stars with
previous high-resolution spectral determinations, we find only a 7 $\pm$ 73 K
difference in effective temperatures, 0.02 $\pm$ 0.09 in log g, and -0.02 $\pm$
0.09 dex in metallicities. We also determined basic kinematic and orbital
parameters for this sample of stars. From the kinematical point of view, almost
all our stars belong to the thin disk substructure of the Milky Way. The
derived galactocentric metallicity gradient is -0.066 $\pm$ 0.024 dex/kpc
(2.5{\sigma} significance) and the vertical metallicity gradient is -0.102
$\pm$ 0.099 dex/kpc (1{\sigma} significance) that comply with the latest
inside-out thin disk formation models, including those with stellar migration
taken into account.
