Reconstructing the Arches cluster - I. Constraining the initial conditions

Harfst, Stefan; Zwart, Simon Portegies; Stolte, A.

doi:10.1111/j.1365-2966.2010.17326.x

Cited by 56 publications

(77 citation statements)

References 25 publications

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“…While the Plummer distribution is well-approximated by a King model with W 0 ≈ 4, young clusters are best represented by King models with W 0 ≥ 7 (e.g. Hillenbrand & Hartmann 1998;Sung & Bessell 2004;Harfst et al 2010). Thus, the term "King model" is used here as an equivalent to King distributions with high W 0 .…”

Section: Cluster Typesmentioning

confidence: 99%

Modes of clustered star formation

Pfalzner

Kaczmarek

Olczak

2012

A&A

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Context. The recent realization that most stars form in clusters, immediately raises the question of whether star and planet formation are influenced by the cluster environment. The stellar density in the most prevalent clusters is the key factor here. Whether dominant modes of clustered star formation exist is a fundamental question. Using near-neighbour searches in young clusters, Bressert and collaborators claim this not to be the case. They conclude that -at least in the solar neighbourhood -star formation is continuous from isolated to densely clustered environments and that the environment plays a minor role in star and planet formation. Aims. We investigate under which conditions near-neighbour searches in young clusters can distinguish between different modes of clustered star formation. Methods. Model star clusters with different memberships and density distributions are set up and near-neighbour searches are performed. We investigate the influence of the combination of different cluster modes, observational biases, and types of diagnostic on the results. Results. We find that the specific cluster density profile, the relative sample sizes, the limitations of the observation, and the choice of diagnostic method decide, whether modelled modes of clustered star formation are detected by near-neighbour searches. For density distributions that are centrally concentrated but span a wide density range (for example, King profiles), separate cluster modes are only detectable under ideal conditions (sample selection, completeness) if the mean density of the individual clusters differs by at least a factor of ∼65. Introducing a central cut-off can lead to an underestimate of the mean density by more than a factor of ten especially in high density regions. The environmental effect on star and planet formation is similarly underestimated for half of the population in dense systems. Conclusions. Local surface-density distributions are a very useful tool for single cluster analyses, but only for high-resolution data. However, in a simultaneous analysis of a sample of cluster environments, it is found that effects of superposition suppress characteristic features very efficiently and thus promote erroneous conclusions. While multiple peaks in the distribution of the local surface density in star forming regions imply the existence of different modes of star formation, the converse conclusion is impossible. Equally, a smooth distribution is no proof of continuous star formation, because such a shape can easily hide modes of clustered star formation.

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Section: Cluster Typesmentioning

confidence: 99%

Modes of clustered star formation

Pfalzner

Kaczmarek

Olczak

2012

A&A

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“…From the extrapolation of the observed stellar mass function, they have estimated photometric masses of about 10 4 M (Habibi et al 2013;Hußmann et al 2012). According to dynamical simulations, the underlying stellar mass is suggested to be as high as 4 × 10 4 M for the Arches cluster (Harfst et al 2010). Spectroscopic age dating of the evolved population of Wolf-Rayet (WR) and giant or supergiant stars suggests an age of 2.5 ± 0.5 Myr (Najarro et al 2004), with a possible upper age limit for the Arches cluster of 4 Myr obtained from supergiant member stars.…”

Section: The Arches and Quintuplet Clustersmentioning

confidence: 99%

Circumstellar discs in Galactic centre clusters: Disc-bearing B-type stars in the Quintuplet and Arches clusters

Stolte

Hussmann

Olczak

et al. 2015

A&A

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We investigate the circumstellar disc fraction as determined from L-band excess observations of the young, massive Arches and Quintuplet clusters residing in the central molecular zone of the Milky Way. The Quintuplet cluster was searched for L-band excess sources for the first time. We find a total of 26 excess sources in the Quintuplet cluster, and 21 sources with L-band excesses in the Arches cluster, of which 13 are new detections. With the aid of proper motion membership samples, the disc fraction of the Quintuplet cluster could be derived for the first time to be 4.0 ± 0.7%. There is no evidence for a radially varying disc fraction in this cluster. In the case of the Arches cluster, a disc fraction of 9.2 ± 1.2% approximately out to the cluster's predicted tidal radius, r < 1.5 pc, is observed. This excess fraction is consistent with our previously found disc fraction in the cluster in the radial range 0.3 < r < 0.8 pc. In both clusters, the host star mass range covers late A-to early B-type stars, 2 < M < 15 M , as derived from J-band photospheric magnitudes. We discuss the unexpected finding of dusty circumstellar discs in these UV intense environments in the context of primordial disc survival and formation scenarios of secondary discs. We consider the possibility that the L-band excess sources in the Arches and Quintuplet clusters could be the high-mass counterparts to T Tauri pre-transitional discs. As such a scenario requires a long pre-transitional disc lifetime in a UV intense environment, we suggest that mass transfer discs in binary systems are a likely formation mechanism for the B-star discs observed in these starburst clusters.

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“…We utilise the observed surface density profile shown in Figure 16 of Espinoza, Selman & Melnick (2009) along with the given best-fit King density profile and parameters, correcting for the number and masses of stars below 10 M with a Kroupa-type IMF. We also use the observed cumulative mass profile given in Figure 3 of Harfst, Portegies Zwart & Stolte (2010), again IMF-corrected for stars below 10 M . 4 M given a SFE of 1/3.…”

Section: Comparison To Galactic Ymcsmentioning

confidence: 99%

Tracing the conversion of gas into stars in Young Massive Cluster Progenitors

Walker

Longmore

Bastian

et al. 2015

Monthly Notices of the Royal Astronomical Society

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Whilst young massive clusters (YMCs; M 10 4 M , age 100 Myr) have been identified in significant numbers, their progenitor gas clouds have eluded detection. Recently, four extreme molecular clouds residing within 200 pc of the Galactic centre have been identified as having the properties thought necessary to form YMCs. Here we utilise far-IR continuum data from the Herschel Infrared Galactic Plane Survey (HiGAL) and millimetre spectral line data from the Millimetre Astronomy Legacy Team 90 GHz Survey (MALT90) to determine their global physical and kinematic structure. We derive their masses, dust temperatures and radii and use virial analysis to conclude that they are all likely gravitationally bound -confirming that they are likely YMC progenitors. We then compare the density profiles of these clouds to those of the gas and stellar components of the Sagittarius B2 Main and North proto-clusters and the stellar distribution of the Arches YMC. We find that even in these cloudsthe most massive and dense quiescent clouds in the Galaxy -the gas is not compact enough to form an Arches-like (M = 2x10 4 M , R ef f = 0.4 pc) stellar distribution. Further dynamical processes would be required to condense the resultant population, indicating that the mass becomes more centrally concentrated as the (proto)-cluster evolves. These results suggest that YMC formation may proceed hierarchically rather than through monolithic collapse.

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Reconstructing the Arches cluster - I. Constraining the initial conditions

Cited by 56 publications

References 25 publications

Modes of clustered star formation

Modes of clustered star formation

Circumstellar discs in Galactic centre clusters: Disc-bearing B-type stars in the Quintuplet and Arches clusters

Tracing the conversion of gas into stars in Young Massive Cluster Progenitors

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