  We report on intriguing photometric properties of Galactic stars observed in
the GALEX satellite's far-UV and near-UV bandbasses as well as from the SDSS
survey and the Kepler Input Catalog. First, the FUV-NUV color distribution of
stars in the Kepler field consists of 2 distinct peaks. Second, curiously, for
stars with spectral types G or later the mean FUV-NUV color becomes much bluer,
contrary to expectation. we have found in two samples of mid-F through K type
stars that ~14-18% of them exhibit FUV-excesses relative to their NUV fluxes
and spectral types. Nearly the same fractions are also discovered among members
of the Kepler Eclipsing Binary Catalog and in the published list of Kepler
Objects of Interest. These UV-excess ("UVe") colors are confirmed by the UV
continuum slopes in GALEX spectra. The SDSS spectra of some UVe stars exhibit
metallic line weakening especially in the blue. This suggests an enhanced
contribution of UV flux relative to photospheric flux of a solar-type single
star. We consider the possibility that the UV excesses originate from various
types of hot stars, including binaries, and strong chromosphere stars that. Our
model atmosphere-derived simulations of colors for binaries with main sequence
pairs with a hot secondary demonstrate that the color loci conflict with the
observed sequence. We are left with the active chromospheres explanation,
whether in active binaries or young stars, as a still tentative explanation for
the UVe stars. We also address the presence of an island of "UV red" stars in
the NUV-g, g-i color diagram. The subpopulation comprising this island are
mainly horizontal branch stars. These objects do not exhibit UV excesses and
therefore have UV colors typical for their spectral types. This subpopulation
appears "red" in the UV because their colors are not pulled to the blue by the
UVe stars.
