Context. Given the closeness of the two open clusters
Aims: We aim to recover the present-day stellar membership in the open clusters
Methods: 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 φ-GRAPE.
Results: We constrain the age, spatial coordinates, 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 seven times larger than the mass of the most reliable members.
Conclusions: We conclude that the two clusters
Astronomy and Astrophysics
- Pub Date:
- October 2020
- open clusters and associations: individual: Collinder 135;
- open clusters and associations: individual: UBC 7;
- methods: numerical;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Astrophysics of Galaxies
- Accepted for publication as a Letter in Astronomy and Astrophysics. 5 pages, 2 figures