Exploring open cluster properties with Gaia and LAMOST
  In Gaia DR2, the unprecedented high-precision level reached in sub-mas for
astrometry and mmag for photometry. Using cluster members identified with these
astrometry and photometry in Gaia DR2, we can obtain a reliable determination
of cluster properties. However, because of the shortcoming of Gaia
spectroscopic observation in dealing with densely crowded cluster region, the
number of radial velocity and metallicity for cluster member stars from Gaia
DR2 is still lacking. In this study, we aim to improve the cluster properties
by combining the LAMOST spectra. In particular, we provide the list of cluster
members with spectroscopic parameters as an add-value catalog in LAMOST DR5,
which can be used to perform detailed study for a better understanding on the
stellar properties, by using their spectra and fundamental properties from the
host cluster. We cross-matched the spectroscopic catalog in LAMOST DR5 with the
identified cluster members in Cantat-Gaudin et al.2018 and then used members
with spectroscopic parameters to derive statistical properties of open
clusters. We obtained a list of 8811 members with spectroscopic parameters and
a catalog of 295 cluster properties. In addition, we study the radial and
vertical metallicity gradient and age-metallicity relation with the compiled
open clusters as tracers, finding slopes of -0.053$\pm$0.004 dex kpc$^{-1}$,
-0.252$\pm$0.039 dex kpc$^{-1}$ and 0.022$\pm$0.008 dex Gyr$^{-1}$,
respectively. Both slopes of metallicity distribution relation for young
clusters (0.1 Gyr < Age < 2 Gyr) and the age-metallicity relation for clusters
within 6 Gyr are consistent with literature results. In order to fully study
the chemical evolution history in the disk, more spectroscopic observations for
old and distant open clusters are needed for further investigation.
