Three candidate double clusters in the LMC: truth or dare?

Dalessandro, E.; Zocchi, Alice; Varri, Anna Lisa; Mucciarelli, A.; Bellazzini, M.; Ferraro, F. R.; Lanzoni, B.; Lapenna, E.; Origlia, L.

doi:10.1093/mnras/stx2892

Cited by 13 publications

(15 citation statements)

References 61 publications

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“…Kounkel & Covey 2019;Kuhn et al 2019), to double/multiple clusters as found in the Magellanic Cloud disks (e.g. Dieball et al 2002;Mucciarelli et al 2012;Dalessandro et al 2018) and finally to massive globulars, can be interpreted as the morphological evidence of different evolutionary phases of the same hierarchical assembly process. This has important implications on our understanding of the environmental conditions (both locally and in the distant Universe) necessary to form massive stellar clusters and, as consequence, on the evolution of stellar cluster properties over cosmic time.…”

Section: Discussionmentioning

confidence: 99%

First phase space portrait of a hierarchical stellar structure in the Milky Way

Dalessandro,

Varri,

Tiongco

et al. 2021

Preprint

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We present the first detailed observational picture of a possible ongoing massive cluster hierarchical assembly in the Galactic disk as revealed by the analysis of the stellar full phase-space (3D positions and kinematics and spectro-photometric properties) of an extended area (6 • diameter) surrounding the well-known h and χ Persei double stellar cluster in the Perseus Arm. Gaia-EDR3 shows that the area is populated by seven co-moving clusters, three of which were previously unknown, and by an extended and quite massive (M ∼ 10 5 M ) halo. All stars and clusters define a complex structure with evidence of possible mutual interactions in the form of intra-cluster over-densities and/or bridges. They share the same chemical abundances (half-solar metallicity) and age (t ∼ 20 Myr) within a small confidence interval and the stellar density distribution of the surrounding diffuse stellar halo resembles that of a cluster-like stellar system. The combination of these evidences suggests that stars distributed within a few degrees from h and χ Persei are part of a common, sub-structured stellar complex that we named LISCA I. Comparison with results obtained through direct N -body simulations suggest that LISCA I may be at an intermediate stage of an ongoing cluster assembly that can eventually evolve in a relatively massive (a few 10 5 M ) stellar system. We argue that such cluster formation mechanism may be quite efficient in the Milky Way and disk-like galaxies and, as a consequence, it has a relevant impact on our understanding of cluster formation efficiency as a function of the environment and redshift.

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Section: Discussionmentioning

confidence: 99%

First phase space portrait of a hierarchical stellar structure in the Milky Way

Dalessandro,

Varri,

Tiongco

et al. 2021

Preprint

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“…For single OCs we adopted f h = r h /RJ , where RJ is the Jacobi radius (RJ = RG(M clu /3MG) 1/3 ; von Hoerner 1957). f h is a useful quantity, since it allows to evaluate the effect of the tidal environment on the clusters' properties (e.g., Dalessandro et al 2018). According to Gieles & Baumgardt (2008), it is related to the fraction of escaping stars at each t rh and therefore to the cluster' star loss rate.…”

Section: Aggregates Of Clusters In the Galactic Contextmentioning

confidence: 99%

“…In this framework, the investigation of cluster pairs can provide crucial information about the mechanisms of cluster formation and evolution (Dalessandro et al 2018). Since binary clusters seem not an uncommon occurrence in the Galaxy, they are potentially interesting objects that could contribute for a proper comprehension on the dynamics of groups of stellar systems (Subramaniam et al 1995).…”

Section: Introductionmentioning

confidence: 99%

Investigating Galactic binary cluster candidates with Gaia EDR3

Angelo,

Santos,

Maia

et al. 2021

Preprint

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A number of stellar open cluster (OC) pairs in the Milky Way occupy similar positions in the phase space (coordinates, parallax and proper motions) and therefore may constitute physically interacting systems. The characterization of such objects based on observational data is a fundamental step towards a proper understanding of their physical status and to investigate cluster pair formation in the Galaxy. In this work, we employed Gaia EDR3 data to investigate a set of 16 OCs distributed as seven stellar aggregates. We determined structural parameters and applied a decontamination technique that allowed to obtain unambiguous lists of member stars. The studied OCs span Galactocentric distances and ages in the ranges 7 R G (kpc) 11 and 7.3 log t 9.2. Eight OCs were found to constitute 4 gravitationally bound pairs (NGC 5617−Trumpler 22, Collinder 394−NGC 6716, Ruprecht 100−Ruprecht 101, NGC 659−NGC 663, the latter being a dynamically unevolved binary) and other 4 clusters constitute 2 interacting, but gravitationally unbound, pairs (King 16−Berkeley 4, NGC 2383−NGC 2384, the latter being a dissolving OC). Other 4 OCs (Dias 1, Pismis 19, Czernik 20, NGC 1857) seem not associated to any stellar aggregates. Apparently, clusters within bound and dynamically evolved pairs tend to present ratios of half-light to tidal radius larger than single clusters located at similar R G , suggesting that mutual tidal interactions may possibly affect their structural parameters. Unbound or dynamically unevolved systems seems to present less noticeable signature of tidal forces on their structure. Moreover, the core radius seems more importantly correlated with the clusters' internal dynamical relaxation process.

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“…Well-known extragalactic examples of binary star clusters include SL 538/NGC 2006 (Dieball & Grebel 1998), NGC 1850 (Fischer et al 1993), and NGC 2136/NGC 2137 (Hilker et al 1995) in the LMC. Recently discovered binary star cluster candidates in the LMC are SL 349/SL 353, SL 385/SL 387/NGC 1922, and NGC 1836/BRHT 4b/NGC 1839 (Dalessandro et al 2018). However, Dalessandro et al (2018) also showed that the double cluster SL 385/SL 387 with the third component NGC 1922 and the double cluster NGC 1836/BRHT 4b with NGC 1839 have an angular separation larger than 120 arcsec.…”

Section: Introductionmentioning

confidence: 99%

“…Recently discovered binary star cluster candidates in the LMC are SL 349/SL 353, SL 385/SL 387/NGC 1922, and NGC 1836/BRHT 4b/NGC 1839 (Dalessandro et al 2018). However, Dalessandro et al (2018) also showed that the double cluster SL 385/SL 387 with the third component NGC 1922 and the double cluster NGC 1836/BRHT 4b with NGC 1839 have an angular separation larger than 120 arcsec. Such a large separation indicates that the influence of external tidal fields has dissociated the constituent star clusters, which have detacheded on a relatively short time scale (Sugimoto & Makino 1989;Bhatia 1990).…”

Section: Introductionmentioning

confidence: 99%

The Formation of Binary Star Clusters in the Milky Way and Large Magellanic Cloud

Darma,

Arifyanto,

Kouwenhoven

2021

Preprint

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Recent observations of young embedded clumpy clusters and statistical identifications of binary star clusters have provided new insights into the formation process and subsequent dynamical evolution of star clusters. The early dynamical evolution of clumpy stellar structures provides the conditions for the origin of binary star clusters. Here, we carry out 𝑁-body simulations in order to investigate the formation of binary star clusters in the Milky Way and in the Large Magellanic Cloud (LMC). We find that binary star clusters can form from stellar aggregates with a variety of initial conditions. For a given initial virial ratio, a higher degree of initial substructure results in a higher fraction of binary star clusters. The number of binary star clusters decreases over time due to merging or dissolution of the binary system. Typically, ∼ 45% of the aggregates evolve into binary/multiple clusters within 𝑡 = 20 Myr in the Milky Way environment, while merely ∼ 30% survives beyond 𝑡 = 50 Myr, with separations 50 pc. On the other hand, in the LMC, ∼ 90% of the binary/multiple clusters survive beyond 𝑡 = 20 Myr and the fraction decreases to ∼ 80% at 𝑡 = 50 Myr, with separations 35 pc. Multiple clusters are also rapidly formed for highly-substructured and expanding clusters. The additional components tend to detach and the remaining binary star cluster merges. The merging process can produce fast rotating star clusters with mostly flat rotation curves that speed up in the outskirts.

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Three candidate double clusters in the LMC: truth or dare?

Cited by 13 publications

References 61 publications

First phase space portrait of a hierarchical stellar structure in the Milky Way

First phase space portrait of a hierarchical stellar structure in the Milky Way

Investigating Galactic binary cluster candidates with Gaia EDR3

The Formation of Binary Star Clusters in the Milky Way and Large Magellanic Cloud

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