Characterization of Kepler targets based on medium-resolution LAMOST
  spectra analyzed with ROTFIT
  In this work we present the results of our analysis of 16,300
medium-resolution LAMOST spectra of late-type stars in the Kepler field with
the aim of determining the stellar parameters, activity level, lithium
atmospheric content, and binarity. We have used a version of the code ROTFIT
specifically developed for these spectra. We provide a catalog with the
atmospheric parameters (Teff, log(g), and [Fe/H]), radial velocity (RV), and
projected rotation velocity (vsini). For cool stars (Teff < 6500 K), we also
calculated the H-alpha and LiI-6708 equivalent width, which are important
indicators of chromospheric activity and evolutionary stage, respectively. We
have derived the RV and atmospheric parameters for 14,300 spectra of 7443
stars. Literature data were used for a quality control of the results. The Teff
and log(g) values are in good agreement with the literature. The [Fe/H] values
appear to be overestimated for metal-poor stars. We propose a relation to
correct the [Fe/H] values derived with ROTFIT. We were able to identify
double-lined binaries, stars with variable RVs, lithium-rich giants, and
emission-line objects. Based on the H-alpha flux, we found 327 active stars. We
detected the LiI-6708 line and measure its equivalent width for 1657 stars,
both giants and stars on the main sequence. Regarding the latter, we performed
a discrete age classification based on the atmospheric lithium abundance and
the upper envelopes of a few open clusters. Among the giants, we found 195
Li-rich stars, 161 of which are reported here for the first time. No
relationship is found between stellar rotation and lithium abundance, which
allows us to rule out merger scenarios as the predominant explanation of the
enrichment of Li in our sample. The fraction of Li-rich giants, about 4%, is
higher than expected.
