Unveiling the Binary Nature of NGC 2323

Abstract

As a well-known open cluster, NGC 2323 (also called M50) has been widely investigated for over a hundred years and has always been considered a classical single cluster. In this work, with the help of Gaia DR3, we study the binary structure nature of this cluster. Although indistinguishable in the spatial space, the small but undeniable difference in the proper motion indicates that they may be two individual clusters. After investigating the properties of the two clusters, it is found that they have very close positions (three-dimensional $\Delta$pos = 12.3 pc, ${\sigma }_{\Delta \mathrm{pos}}=3.4$ pc) and similar tangential velocities (two-dimensional $\Delta$V = 2.2 km s${}^{-1}$, ${\sigma }_{\Delta \mathrm{V}}=0.02$ km s${}^{-1}$), indicating the existence of their physical association. Moreover, the best isochrone fitting ages of the two clusters are the same (158 Myr), further proving their possibly common origin. To comprehensively understand the formation and evolution of this binary cluster, we employ the PETAR $N$-body code to trace back their birthplace and deduce their dynamical evolutionary fate. With observational mean cluster properties, the simulations suggest that they may form together, and then orbit each other as a binary cluster for over 200 Myr. After that, because of their gradual mass loss, the two clusters will eventually separate and evolve into two independent clusters. Meanwhile, the numerical $N$-body simulation suggests that the less massive cluster is unlikely to be the cluster tidal tails created by the differential rotation of the Milky Way.

14 pages, 8 figures

References in corpus (19)

• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• galpy: A Python Library for Galactic Dynamics
• Painting a portrait of the Galactic disc with its stellar clusters
• Improving the open cluster census. II. An all-sky cluster catalogue with Gaia DR3
• A catalog of newly identified star clusters in GAIA DR2
• Hunting for open clusters in \textit{Gaia} DR2: $582$ new OCs in the Galactic disc
• PeTar: a high-performance N-body code for modeling massive collisional stellar systems
• The Physics of Star Cluster Formation and Evolution
• Improving the open cluster census. I. Comparison of clustering algorithms applied to Gaia DR2 data
• Revisiting the mass of open clusters with \emph{Gaia} data
• Diagnosing the Stellar Population and Tidal Structure of the Blanco1 Star Cluster
• Asymmetrical tidal tails of open star clusters: stars crossing their cluster's prah challenge Newtonian gravitation
• The substructure and halo population of the Double Cluster $h$ and $\chi$ Persei
• New Open Cluster candidates Found in Galactic Disk Using Gaia DR2/EDR3 Data
• MiMO: Mixture Model for Open Clusters in Color-Magnitude Diagrams
• Binary open clusters in the Gaia data
• The list of possible double and multiple open clusters between galactic longitudes 240 and 270 degrees
• Investigating Galactic binary cluster candidates with Gaia EDR3
• Discovery of extended structure around open cluster COIN-Gaia 13 based on Gaia EDR3