Mass Functions and Photometric Binaries in Nine Open Clusters

Sharma, Saurabh; Pandey, A. K.; Ogura, K.; Aoki, Tsutomu; Pandey, Kavita; Sandhu, Tejbir Singh; Sagar, Ram

doi:10.1088/0004-6256/135/5/1934

Cited by 56 publications

(66 citation statements)

References 40 publications

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“…To avoid the large uncertainties in some of the stars, we did not consider stars having photometric error larger than 0.04, 0.03 and 0.02 mag in U, B and V bands, respectively. We fit intrinsic zero-age main sequence (ZAMS) isochrones given by Schmidt -Kaler (1982) The value of reddening vector X for the clusters NGC 2360 and Be 68 are found to be close to the normal value of 0.72 (Garcia et al 1988;Turner 1989) but we yield a slope of 0.46 for NGC 381 that significantly low than the normal value. This implies that the dust grain size is larger than average size in the direction of the cluster NGC 381.…”

Section: Reddening Determination: (U-b) Vs (B-v)mentioning

confidence: 85%

Photometric and kinematic study of the three intermediate age open clusters NGC 381, NGC 2360, and Berkeley 68

Maurya

Joshi

2020

Monthly Notices of the Royal Astronomical Society

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We present UBVR c I c photometric study of three intermediate age open star clusters NGC 381, NGC 2360, and Berkeley 68 (Be 68). We examine the cluster membership of stars using recently released Gaia DR2 proper motions and obtain a total of 116, 332, and 264 member stars in these three clusters. The mean reddening of E(B − V) = 0.36±0.04, 0.08±0.03, and 0.52±0.04 mag are found in the direction of these clusters where we observe an anomalous reddening towards NGC 381. We fitted the solar metallicity isochrones to determine age and distance of the clusters which are found to be log(Age) = 8.65±0.05, 8.95±0.05, and 9.25±0.05 yr with the respective distance of 957±152, 982±132, and 2554±387 pc for the clusters NGC 381, NGC 2360, and Be 68. A two-stage power law in the mass function (MF) slope is observed in the cluster NGC 381, however, we observe only a single MF slope in the clusters NGC 2360 and Be68. To study a possible spatial variation in the slope of MF we estimate slopes separately in the inner and the outer regions of these clusters and notice a steeper slope in outer region. The dynamic study of these clusters reveals deficiency of lowmass stars in their inner regions suggesting the mass segregation process in all these clusters. The relaxation times of 48.5, 78.9, and 87.6 Myr are obtained for the clusters NGC 381, NGC 2360, and Be 68, respectively which are well below to their respective ages. This suggests that all the clusters are dynamically relaxed.

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Section: Reddening Determination: (U-b) Vs (B-v)mentioning

confidence: 85%

Photometric and kinematic study of the three intermediate age open clusters NGC 381, NGC 2360, and Berkeley 68

Maurya

Joshi

2020

Monthly Notices of the Royal Astronomical Society

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“…They found that the observed mass segregation of the sample of young clusters studied could be explained on the basis of the dynamics. It was found by Bonatto & Bica (2005b) and Sharma et al (2008) that the MF slopes (in the outer region as well as the whole cluster) undergo an exponential decay with the evolutionary parameter τ= t age / t relax and that the evaporation of low‐mass members from outer regions of the clusters is not significant at larger Galactocentric distances of 9–10.8 kpc. The parameter τ is an evolutionary parameter (Bonatto & Bica 2005a) which indicates the extent to which the cluster has relaxed.…”

Section: Introductionmentioning

confidence: 89%

Mass segregation in diverse environments

Hasan

2011

Monthly Notices of the Royal Astronomical Society

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In this paper, using 2MASS photometry, we study the mass functions $\phi(M) = dN/dM \propto M^{-\alpha}$ of a sample of nine clusters of ages varying from 4 Myr--1.2 Gyr and Galactocentric distances from 6--12 kpc. We look for evidence of mass segregation in these clusters by tracing the variation in the value of $\alpha$ in different regions of the cluster as a function of the parameter $\tau = t_{age}/t_{relax}$ (where $t_{age}$ is the age of the cluster and $t_{relax}$ is the relaxation time of the cluster), Galactocentric distance, age and size of the cluster. The value of $\alpha$ value increases with age and $\tau$ and fits straight lines with slopes $m$ and y-intercepts $c$ given by $m=0.40\pm0.03$, $c=-1.86\pm0.27$ and $m=0.01\pm0.001$, $c=-0.85\pm0.02$, respectively and is a clear indicator of the dynamical processes involved. The confidence level of the Pearson's product-moment correlation of $\alpha$ with age is 0.76 with p=0.002 and with $\tau$ is 0.71 with p=0.007. The value of $\alpha$ also increases with Galactocentric distance, indicating the presence of a larger relative number of low mass stars in clusters at larger Galactocentric distances. We find two clusters, viz. IC 1805 and NGC 1893, with evidence of primordial or early dynamical mass segregation. Implications of primordial mass segregation on the formation of massive stars and recent results supporting early dynamical mass segregation are discussed.Comment: Accepted MNRAS, 28 page

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“…core radius) can be found. This method has been used in many studies (Hillenbrand 1997; Pinfield, Jameson & Hodgkin 1998; Raboud 1999; Adams et al 2001; Littlefair et al 2003; Sharma et al 2008). However, the accuracy of this method has been brought into question by Gouliermis et al (2004), who show that this method is highly dependent on the number of mass bins, the size of the bins and on the models used to fit the density profile.…”

Section: Mass Segregationmentioning

confidence: 99%

Using the minimum spanning tree to trace mass segregation

Allison¹,

Goodwin²,

Parker³

et al. 2009

Monthly Notices of the Royal Astronomical Society

231

301

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We present a new method to detect and quantify mass segregation in star clusters. It compares the minimum spanning tree (MST) of massive stars with that of random stars. If mass segregation is present, the MST length of the most massive stars will be shorter than that of random stars. This difference can be quantified (with an associated significance) to measure the degree of mass segregation. We test the method on simulated clusters in both 2D and 3D and show that the method works as expected. We apply the method to the Orion Nebula Cluster (ONC) and show that the method is able to detect the mass segregation in the Trapezium with a `mass segregation ratio' \Lambda_{MSR}=8.0 \pm 3.5 (where \Lambda_{MSR}=1 is no mass segregation) down to 16 \Msun, and also that the ONC is mass segregated at a lower level (~2.0 \pm 0.5) down to 5 \Msun. Below 5 \Msun we find no evidence for any further mass segregation in the ONC.Comment: Accepted in MNRA

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Mass Functions and Photometric Binaries in Nine Open Clusters

Cited by 56 publications

References 40 publications

Photometric and kinematic study of the three intermediate age open clusters NGC 381, NGC 2360, and Berkeley 68

Photometric and kinematic study of the three intermediate age open clusters NGC 381, NGC 2360, and Berkeley 68

Mass segregation in diverse environments

Using the minimum spanning tree to trace mass segregation

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