Star-by-star dynamical evolution of the physical pair of the Collinder 135 and UBC 7 open clusters
Berczik, Peter; Just, Andreas; Kovaleva, Dana A.; Piskunov, Anatoly E.; Kharchenko, Nina V.; Ishchenko, Maryna; Polyachenko, Evgeny; Postnikova, Ekaterina; Borodina, Olga; Omarov, Chingis; Sobodar, Olexandr
Poland, Kazakhstan, Germany, United States, Hungary
Abstract
Context. In a previous paper using Gaia DR2 data, we demonstrated that the two closely situated open clusters Collinder 135 and UBC 7 might have formed together about 50 Myr ago.
Aims: In this work, we performed star-by-star dynamical modelling of the evolution of the open clusters Collinder 135 and UBC 7 from their supposed initial state to their present-day state, reproducing observational distributions of members.
Methods: Modelling of the Collinder 135 and UBC 7 dynamical evolution was done using the high-order parallel N-body code φ-GPU with up-to-date stellar evolution. Membership and characteristics of the clusters were acquired based on Gaia DR3 data.
Results: The comparison of the present-day radial cumulative star count obtained from the N-body simulations with the current observational data gave us full consistency of the model with observational data, especially in the central 8 pc, where 80% of the stars reside. The proper motion velocity components obtained from the N-body simulations of the stars are also quite consistent with the observed distributions and error bars.
Conclusions: These results show that our numerical modelling is able to reproduce the open clusters' current complex 6D observed phase-space distributions with a high level of confidence. Thus, the model demonstrates that the hypothesis of a common origin of Collinder 135 and UBC 7 complies with present-day observational data.