Open clusters and the galactic disk
  It is textbook knowledge that open clusters are conspicuous members of the
thin disk of our Galaxy, but their role as contributors to the stellar
population of the disk was regarded as minor. Starting from a homogenous
stellar sky survey, the ASCC-2.5, we revisited the population of open clusters
in the solar neighbourhood from scratch. In the course of this enterprise we
detected 130 formerly unknown open clusters, constructed volume- and
magnitude-limited samples of clusters, re-determined distances, motions, sizes,
ages, luminosities and masses of 650 open clusters. We derived the present-day
luminosity and mass functions of open clusters (not the stellar mass function
in open clusters), the cluster initial mass function CIMF and the formation
rate of open clusters. We find that open clusters contributed around 40 percent
to the stellar content of the disk during the history of our Galaxy. Hence,
open clusters are important building blocks of the Galactic disk.
