Study of the open clusters in Kepler prime field

We present a detailed study of NGC 6791, NGC 6811, NGC 6819, and NGC 6866, the four open clusters that are located in the Kepler prime field. We use new CCD UBV(RI)KC photometry, which was combined with Gaia EDR3 photometric/astrometric data, to derive the astrophysical parameters with two-independent methods - one of them the fitCMD algorithm. Furthermore, we provide among others estimates of the mass and mass function, the cluster structure, derive the cluster orbits, and discuss the cluster dynamics. All objects belong to the older open cluster population ( similar to 1-7 Gyr), are in an advanced dynamical stage with signs of mass se gre gation, and are located close to the solar circle, but show a large range in respect of radii, member stars or observed cluster mass (similar to 100 -2000 M-?). For the three younger objects, we were also able to provide photometric metallicity estimates, which confirms their status as clusters with a roughly solar metallicity. The most outstanding object is clearly NGC 6791, a very old cluster with a high metallicity at a distance of about 4.5 kpc from the Sun. We estimate a probable radial migration by about 7 kpc, resulting in a birth position close to the Galactic centre.

Automated summary

We conducted a detailed study of four open clusters, NGC 6791, NGC 6811, NGC 6819, and NGC 6866, located in the Kepler prime field. Using new CCD UBV(RI)KC photometry combined with Gaia EDR3 data, we derived astrophysical parameters and discussed various aspects of these clusters, including mass, cluster structure, orbits, and dynamics. NGC 6791 stands out as a very old cluster with high metallicity and a possible birth position near the Galactic center.