Volume 624, April 2019
|Number of page(s)||7|
|Section||Letters to the Editor|
|Published online||16 April 2019|
Letter to the Editor
Extended stellar systems in the solar neighborhood
III. Like ships in the night: the Coma Berenices neighbor moving group⋆
Department of Astrophysics, University of Vienna, Türkenschanzstrasse 17, 1180 Wien, Austria
2 Radcliffe Institute for Advanced Study, Harvard University, 10 Garden Street, Cambridge, MA 02138, USA
3 Data Science at Uni Vienna, Faculty of Earth Sciences Geography and Astronomy, University of Vienna, Austria
Accepted: 12 March 2019
We report the discovery of a kinematically cold group of stars, located in the immediate neighborhood of the well-known star cluster Coma Berenices (Mel 111). The new group identified in tangential velocity space as measured by Gaia contains at least 177 coeval members distributed in two subgroups, and appears as a flattened structure parallel to the plane, stretching for about 50 pc. More remarkably, the new group, which appears to have formed about 300 Myr later than Mel 111 in a different part of the Galaxy, will share essentially the same volume with the older cluster when the centers of both groups will be at their closest in 13 Myr. This will result in the mixing of two unrelated populations with different metallicities. The phase of cohabitation for these two groups is about 20–30 Myr, after which the two populations will drift apart. We estimate that temporal cohabitation of such populations is not a rare event in the disk of the Milky Way, and of the order of once per Galactic revolution. Our study also unveils the tidal tails of the Mel 111 cluster.
Key words: stars: kinematics and dynamics / solar neighborhood / open clusters and associations: individual: Coma Berenices
Full Table A.2 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (22.214.171.124) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/624/L11
© ESO 2019
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