The Dissolution of Open Star Clusters in the Tidal Field of the Galaxy

• Applicant: Professor Dr. Andreas Just
• Subject Area: Astrophysics and Astronomy
• Term: from 2011 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 192963324

Open star clusters (OCs) represent a significant portion of the stellar population of the Milky Way disc. Ages, metallicities, and distances of OCs can be determined easily as well as kinematics for nearby clusters. The mass determination is much more uncertain due to the unobserved lower main sequence, possible mass segregation and the high level of field contamination at low galactic latitudes. A recent new approach to apply a simple dynamical mass estimate of tidally limited clusters to an unbiased OC catalogue yield significantly higher cluster masses compared to the classical methods. In this project we investigate the dissolution of OCs with numerical simulations as realistic as possible with high performance special hardware computers. In contrast to the classical results the new numerical investigations are based on a star-by-star simulation including stellar evolution and covering a much larger range of initial conditions. This allows more distinct quantitative predictions of cluster shape, mass and mass loss. The application to the OC catalogue will give a precise determination of the cluster mass function, lifetimes and the cluster formation rate in the solar neighbourhood. An independent test of the models would be the identification of clumps in the tidal tails of dissolving OCs predicted by theory. We will analyse whether these clumps are observable as moving groups.

• DFG Programme: Research Grants