Collinder 135 and UBC 7: A Physical Pair of Open Clusters
| Autor: | Peter Berczik, Nina V. Kharchenko, E. S. Postnikova, Kseniia Sysoliatina, A. E. Piskunov, M. V. Ishchenko, Sabine Reffert, Evgeny Polyachenko, Dana Kovaleva, Andreas Just |
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| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Physics
010308 nuclear & particles physics media_common.quotation_subject FOS: Physical sciences Astronomy and Astrophysics Context (language use) Astrophysics Kinematics 01 natural sciences Astrophysics - Astrophysics of Galaxies Coincidence Astrophysics - Solar and Stellar Astrophysics Space and Planetary Science Sky Spatial reference system Phase space Astrophysics of Galaxies (astro-ph.GA) 0103 physical sciences Cluster (physics) 010303 astronomy & astrophysics Solar and Stellar Astrophysics (astro-ph.SR) media_common Open cluster |
| Popis: | Given the closeness of the two open clusters Cr 135 and UBC 7 on the sky, we investigate the possibility of the two clusters to be physically related. We aim to recover the present-day stellar membership in the open clusters Collinder 135 and UBC 7 (300 pc from the Sun), to constrain their kinematic parameters, ages and masses, and to restore their primordial phase space configuration. The most reliable cluster members are selected with our traditional method modified for the use of Gaia DR2 data. Numerical simulations use the integration of cluster trajectories backwards in time with our original high order Hermite4 code \PGRAPE. We constrain the age, spatial coordinates and velocities, radii and masses of the clusters. We estimate the actual separation of the cluster centres equal to 24 pc. The orbital integration shows that the clusters were much closer in the past if their current line-of-sight velocities are very similar and the total mass is more than 7 times larger the mass of the determined most reliable members. We conclude that the two clusters Cr 135 and UBC 7 might very well have formed a physial pair, based on the observational evidence as well as numerical simulations. The probability of a chance coincidence is only about $2\%$. Accepted for publication as a Letter in Astronomy and Astrophysics. 5 pages, 2 figures |
| Databáze: | OpenAIRE |
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