The formation and evolution of small star clusters

Kirk, Helen; Offner, Stella S. R.; Redmond, Kayla

doi:10.1093/mnras/stu052

Cited by 38 publications

(54 citation statements)

References 61 publications

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“…Numerical simulations have varied predictions on whether or not there is primordial mass segregation in clusters. Some simulations find mass segregation of stars/sink cells in clusters from very early times (e.g., Maschberger & Clarke 2011;Girichidis et al 2012;Kirk et al 2014;Myers et al 2014). Other simulators find no evidence of mass segregation (e.g., Parker et al 2014), while find that evidence for or against mass segregation depends on the method used to measure it.…”

Section: Discussionmentioning

confidence: 99%

The JCMT Gould Belt Survey: Dense Core Clusters in Orion B

Kirk

Johnstone

Francesco

et al. 2016

ApJ

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The James Clerk Maxwell Telescope Gould Belt Legacy Survey obtained SCUBA-2 observations of dense cores within three sub-regions of OrionB: LDN1622, NGC2023/2024, and NGC2068/2071, all of which contain clusters of cores. We present an analysis of the clustering properties of these cores, including the two-point correlation function and Cartwright's Q parameter. We identify individual clusters of dense cores across all three regions using a minimal spanning tree technique, and find that in each cluster, the most massive cores tend to be centrally located. We also apply the independent M-Σ technique and find a strong correlation between core mass and the local surface density of cores. These two lines of evidence jointly suggest that some amount of mass segregation in clusters has happened already at the dense core stage.

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Section: Discussionmentioning

confidence: 99%

The JCMT Gould Belt Survey: Dense Core Clusters in Orion B

Kirk

Johnstone

Francesco

et al. 2016

ApJ

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“…The presence (or absence) of such massive stars can affect the stellar content and overall evolution of low-mass clusters (Pelupessy & Portegies Zwart 2012). As voracious consumers of star-forming material, the most massive stars may form early-on (Kirk et al 2014), thereby increasing the likelihood that they will affect the gas content of a star-forming region before large numbers of lower mass stars have formed.…”

Section: Summary and Discussionmentioning

confidence: 99%

The Distribution of Main Sequence and Premain Sequence Stars in the Young Anticenter Cluster NGC 2401

Davidge¹

2015

Publications of the Astronomical Society of the Pacific

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ABSTRACT. Images obtained with the Gemini Multiobject Spectrograph on Gemini South are used to examine the photometric properties and spatial distributions of main sequence (MS) and premain sequence (PMS) objects in the star cluster NGC 2401. The data sample several magnitudes fainter than previous studies and a large population of candidate PMS (cPMS) stars are identified. The cPMS stars are traced out to 2.4′ from the cluster center and have a flatter spatial distribution than the brightest MS stars near the cluster center. The luminosity function of all MS and candidate PMS stars can be matched by a model that assumes a solar neighborhood mass function, suggesting that NGC 2401 has not yet shed significant numbers of members with masses ≥0:5 M ⊙ . The frequency of wide binaries among the MS stars is ∼3× higher than among the cPMS stars. It is argued that the difference in the spatial distributions of MS and PMS objects is not the consequence of secular dynamical evolution or structural evolution driven by near-catastrophic mass loss. Rather, it is suggested that the different spatial distributions of these objects is the fossil imprint of primordial subclustering that arises naturally if massive stars form preferentially in the highest density central regions of a protocluster.

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“…In contrast, NGC 2023/NGC 2024 displays high levels of mass segregation for the four most massive cores, with the 10-20 most massive cores also mass segregated to a high level. Kirk et al (2016b) find that all three regions in Orion B are mass segregated, according to the group segregation method developed by Kirk & Myers (2011) and Kirk et al (2014). This method is very different to conventional methods of defining mass segregation, such as quantifying the change in the IMF as a function of distance from the centre of a star-forming region.…”

Section: Comparison With Previous Workmentioning

confidence: 99%

“…Kirk et al (2016b) found that none of the three subregions are spatially substructured according the Q-parameter (Cartwright & Whitworth 2004;Cartwright 2009), which is surprising as all three regions appear visually substructured. The authors also claim to find mass segregation of the cores, but using the group segregation ratio method (Kirk & Myers 2011;Kirk, Offner & Redmond 2014). However, Parker & Goodwin (2015) find serious flaws in this technique, to the extent that it may not accurately find or quantify mass segregation in spatially substructured star-forming regions.…”

Section: Introductionmentioning

confidence: 99%

On the spatial distributions of dense cores in Orion B

Parker

2018

Monthly Notices of the Royal Astronomical Society

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We quantify the spatial distributions of dense cores in three spatially distinct areas of the Orion B star-forming region. For L1622, NGC 2068/NGC 2071, and NGC 2023/NGC 2024, we measure the amount of spatial substructure using the Q-parameter and find all three regions to be spatially substructured (Q < 0.8). We quantify the amount of mass segregation using MSR and find that the most massive cores are mildly mass segregated in NGC 2068/NGC 2071 ( MSR ∼ 2), and very mass segregated in NGC 2023/NGC 2024 ( MSR = 28 +13 −10 for the four most massive cores). Whereas the most massive cores in L1622 are not in areas of relatively high surface density, or deeper gravitational potentials, the massive cores in NGC 2068/NGC 2071 and NGC 2023/NGC 2024 are significantly so. Given the low density (10 cores pc −2 ) and spatial substructure of cores in Orion B, the mass segregation cannot be dynamical. Our results are also inconsistent with simulations in which the most massive stars form via competitive accretion, and instead hint that magnetic fields may be important in influencing the primordial spatial distributions of gas and stars in star-forming regions.

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The formation and evolution of small star clusters

Cited by 38 publications

References 61 publications

The JCMT Gould Belt Survey: Dense Core Clusters in Orion B

The JCMT Gould Belt Survey: Dense Core Clusters in Orion B

The Distribution of Main Sequence and Premain Sequence Stars in the Young Anticenter Cluster NGC 2401

On the spatial distributions of dense cores in Orion B

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