Open clusters with proper motions fully separated from the field stars using Gaia DR2

Abstract

The study of open star clusters makes us understand a lot about the composition and construction of the Milky Way Galaxy. Thanks to the Gaia DR2 database that helps us to get the genetic members of star clusters using their proper motions and parallaxes, estimating their physical properties in a very accurate way. This study aims to detect the reasons that make proper motions value of a cluster is completely separated from the background field stars and not melted in. We studied a large sample of open stellar clusters taken from Dias catalog and drawing the vector point diagrams using the astrometric data of Gaia DR2. Marking the separated clusters and melted ones and study their mean parameters in each galactic quadrant.