Issue |
A&A
Volume 693, January 2025
|
|
---|---|---|
Article Number | A317 | |
Number of page(s) | 9 | |
Section | Galactic structure, stellar clusters and populations | |
DOI | https://doi.org/10.1051/0004-6361/202452962 | |
Published online | 29 January 2025 |
Unveiling the binary nature of NGC 2323
1
Astrophysics Division, Shanghai Astronomical Observatory, Chinese Academy of Sciences,
80 Nandan Road,
Shanghai
200030,
PR China
2
School of Astronomy and Space Science, University of Chinese Academy of Sciences,
No. 19A, Yuquan Road,
Beijing
100049,
PR China
3
Institut de Ciències del Cosmos, Universitat de Barcelona (ICCUB),
Martí i Franquès 1,
08028
Barcelona,
Spain
4
School of Physics and Astronomy, Sun Yat-sen University,
Daxue Road,
Zhuhai
519082,
China
5
CSST Science Center for the Guangdong-Hong Kong-Macau Greater Bay Area,
Zhuhai
519082,
China
6
Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg,
Mönchhofstr. 12–14,
69120
Heidelberg,
Germany
7
Departament de Física Quàntica i Astrofísica (FQA), Universitat de Barcelona (UB),
C Martí i Franquès 1,
08028
Barcelona,
Spain
8
Institut d’Estudis Espacials de Catalunya (IEEC),
Edifici RDIT, Campus UPC,
08860
Castelldefels (Barcelona),
Spain
9
Xinjiang Astronomical Observatory, Chinese Academy of Sciences,
Urumqi
830011,
China
10
School of Physics and Astronomy, China West Normal University,
No. 1 Shida Road,
Nanchong
637002,
China
★ Corresponding authors; qinsongmei@shao.ac.cn; jzhong@shao.ac.cn
Received:
11
November
2025
Accepted:
17
December
2024
Context. 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.
Aims. We studied the binary structure nature of NGC 2323 with Gaia Data Release 3 (DR3).
Methods. We discovered the binary structure of NGC 2323 by the HDBSCAN algorithm based on the astrometric and photometric data from Gaia DR3. Then we employed the PETAR N-body code to investigate its binary structure origin.
Results. We found that NGC 2323 consists of two distinct subclusters (NGC 2323-a and NGC 2323-b) that are still gravitationally bound. They have very close positions (three-dimensional Δpos = 12.3 pc, σΔpos = 3.4 pc) and similar tangential velocities (two-dimensional ΔV = 2.2 km s−1, σΔV = 0.02 km s−1). The best isochrone fitting ages of the two clusters are the same (158 Myr), further proving their possibly common origin. 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.
Key words: open clusters and associations: general / open clusters and associations: individual: NGC 2323
© The Authors 2025
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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