Speaker
Description
We present the discovery and characterization of debris stellar groups around
the Double Cluster h (NGC 869) and chi (NGC 884) Persei to diagnose the formation
and dynamical evolution of binary star clusters. Stars are formed in groups, and
those surviving the emergence out of the molecular clouds become a star cluster.
Open star clusters, primarily located in the Galactic disk, are particularly
vulnerable to continuous disintegration: (1) Two-body relaxation among member stars
leads to ejection of low-massive members, ever shallowing the gravitational
potential, (2) External tidal disturbances exacerbate the situation, manifest by
tidal tails or debris stellar groups sharing the same volume and motion with the
parental cluster. Then-members of dissolved clusters constitute the Galactic field
stars. While the majority of stars have companions, and pair galaxies are common,
double star clusters are relatively rare. Using the astrometry and photometry from the
latest space mission Gaia (Data Release 3), we identified more than a handful of
distinct groups, some found for the first time, with distance and space motion
consistent with those of the Double Cluster. We derived for each group its size,
age, and number of members. We offer convincing evidence of some groups being
ejected as the cluster pair orbits each other.
| Section | Stars/Star Clusters |
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