scholarly journals Astrometric and photometric study of NGC 6067, NGC 2506, and IC 4651 open clusters based on wide-field ground and Gaia DR2 data

2019 ◽  
Vol 490 (1) ◽  
pp. 1383-1396 ◽  
Author(s):  
Geeta Rangwal ◽  
R K S Yadav ◽  
Alok Durgapal ◽  
D Bisht ◽  
D Nardiello
Keyword(s):  
Function Analysis ◽  
Mass Range ◽  
Mass Function ◽  
Open Clusters ◽  
Wide Field ◽  
Open Star Clusters ◽  
Potential Models ◽  
Open Star ◽  
Astrometric Data ◽  
Gaia Dr2

ABSTRACT We present an analysis of three southern open star clusters NGC 6067, NGC 2506, and IC 4651 using wide-field photometric and Gaia DR2 astrometric data. They are poorly studied clusters. We took advantage of the synergy between Gaia DR2 high precision astrometric measurements and ground-based wide-field photometry to isolate cluster members and further study these clusters. We identify the cluster members using proper motions, parallax and colour–magnitude diagrams. Mean proper motion of the clusters in μαcosδ and μδ is estimated as −1.90 ± 0.01 and −2.57 ± 0.01 mas yr−1 for NGC 6067, −2.57 ± 0.01, and 3.92 ± 0.01 mas yr−1 for NGC 2506 and −2.41 ± 0.01 and −5.05 ± 0.02 mas yr−1 for IC 4651. Distances are estimated as 3.01 ± 0.87, 3.88 ± 0.42, and 1.00 ± 0.08 kpc for the clusters NGC 6067, NGC 2506, and IC 4651, respectively, using parallaxes taken from Gaia DR2 catalogue. Galactic orbits are determined for these clusters using Galactic potential models. We find that these clusters have circular orbits. Cluster radii are determined as 10 arcmin for NGC 6067, 12 arcmin for NGC 2506, and 11 arcmin for IC 4651. Ages of the clusters estimated by isochrones fitting are 66 ± 8 Myr, 2.09 ± 0.14 Gyr, and 1.59 ± 0.14 Gyr for NGC 6067, NGC 2506, and IC 4651, respectively. Mass function slope for the entire region of cluster NGC 2506 is found to be comparable with the Salpeter value in the mass range of 0.77–1.54 M⊙. The mass function analysis shows that the slope becomes flat when one goes from halo to core region in all the three clusters. A comparison of dynamical age with cluster’s age indicates that NGC 2506 and IC 4651 are dynamically relaxed clusters.

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

2020 ◽  
Vol 494 (4) ◽  
pp. 4713-4729 ◽  
Author(s):  
Jayanand Maurya ◽  
Y C Joshi
Keyword(s):  
Relaxation Times ◽  
Outer Region ◽  
Mass Function ◽  
Open Clusters ◽  
Open Star Clusters ◽  
Low Mass Stars ◽  
Cluster Membership ◽  
Open Star ◽  
Solar Metallicity ◽  
Mass Segregation

ABSTRACT We present UBVRcIc 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 is 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 low-mass 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.

scholarly journals An optical observational cluster mass function at z ∼ 1 with the ORELSE survey

2021 ◽  
Vol 502 (3) ◽  
pp. 3942-3954
Author(s):  
D Hung ◽  
B C Lemaux ◽  
R R Gal ◽  
A R Tomczak ◽  
L M Lubin ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Large Scale ◽  
Near Infrared ◽  
Function Analysis ◽  
Voronoi Tessellation ◽  
Cosmological Parameters ◽  
Mass Range ◽  
Mass Function ◽  
Cluster Mass ◽  
Theoretical Mass

ABSTRACT We present a new mass function of galaxy clusters and groups using optical/near-infrared (NIR) wavelength spectroscopic and photometric data from the Observations of Redshift Evolution in Large-Scale Environments (ORELSE) survey. At z ∼ 1, cluster mass function studies are rare regardless of wavelength and have never been attempted from an optical/NIR perspective. This work serves as a proof of concept that z ∼ 1 cluster mass functions are achievable without supplemental X-ray or Sunyaev-Zel’dovich data. Measurements of the cluster mass function provide important contraints on cosmological parameters and are complementary to other probes. With ORELSE, a new cluster finding technique based on Voronoi tessellation Monte Carlo (VMC) mapping, and rigorous purity and completeness testing, we have obtained ∼240 galaxy overdensity candidates in the redshift range 0.55 < z < 1.37 at a mass range of 13.6 < log (M/M⊙) < 14.8. This mass range is comparable to existing optical cluster mass function studies for the local universe. Our candidate numbers vary based on the choice of multiple input parameters related to detection and characterization in our cluster finding algorithm, which we incorporated into the mass function analysis through a Monte Carlo scheme. We find cosmological constraints on the matter density, Ωm, and the amplitude of fluctuations, σ8, of $\Omega _{m} = 0.250^{+0.104}_{-0.099}$ and $\sigma _{8} = 1.150^{+0.260}_{-0.163}$. While our Ωm value is close to concordance, our σ8 value is ∼2σ higher because of the inflated observed number densities compared to theoretical mass function models owing to how our survey targeted overdense regions. With Euclid and several other large, unbiased optical surveys on the horizon, VMC mapping will enable optical/NIR cluster cosmology at redshifts much higher than what has been possible before.

scholarly journals The Galactic System of Open Star Clusters: A Personal Perspective

2002 ◽  
Vol 207 ◽  
pp. 24-37
Author(s):  
Randy L. Phelps
Keyword(s):  
Milky Way ◽  
Star Clusters ◽  
Open Clusters ◽  
Personal Perspective ◽  
Open Star Clusters ◽  
Nearby Star ◽  
Open Star ◽  
Galactic System ◽  
The Status ◽  
Open Star Cluster

Technology is now allowing for the investigation of star clusters outside of the Milky Way. As attention turns to the extragalactic star clusters, a perception that the system of star clusters in the Milky Way is well understood may grow, resulting in the neglect of these important objects. In this review, the status of our understanding of the Milky Way's open star cluster population will be discussed. Specifically, I will attempt to illustrate not only the important information that can and must be learned from these nearby star clusters, but also the degree to which our understanding of the Galactic open clusters remains incomplete.

scholarly journals Structure and Mass Function of Open Cluster NGC 6910

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Harmeen Kaur ◽  
Saurabh Sharma ◽  
Alok K. Durgapal
Keyword(s):  
Molecular Clouds ◽  
Luminosity Function ◽  
Open Cluster ◽  
Mass Function ◽  
Open Clusters ◽  
Initial Mass Function ◽  
Wide Field ◽  
Evolutionary Models ◽  
Star Forming ◽  
Initial Results

NGC 6910 is located in a Cygnus X region, which is a ∼10◦ complex of actively star forming molecular clouds and young clusters, located at a distance of about 1.7 kpc (Reipurth & Schneider 2008). Open clusters possess many favorable characteristics for initial mass function (IMF) studies. The observed mass function of a star cluster can in principle be determined from the observed luminosity function (LF) using theoretical stellar evolutionary models. Here, we are presenting our initial results related to structure parameters, extinction, distance and mass function of open cluster NGC 6910 based on the deep and wide field mosaic images taken from 1.0m Sampurnand telescope of ARIES, India.

scholarly journals Structure and Mass Function of Open Cluster NGC 6910

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Harmeen Kaur ◽  
Saurabh Sharma ◽  
Alok K. Durgapal
Keyword(s):  
Molecular Clouds ◽  
Luminosity Function ◽  
Open Cluster ◽  
Mass Function ◽  
Open Clusters ◽  
Initial Mass Function ◽  
Wide Field ◽  
Evolutionary Models ◽  
Star Forming ◽  
Initial Results

NGC 6910 is located in a Cygnus X region, which is a ∼10◦ complex of actively star forming molecular clouds and young clusters, located at a distance of about 1.7 kpc (Reipurth & Schneider 2008). Open clusters possess many favorable characteristics for initial mass function (IMF) studies. The observed mass function of a star cluster can in principle be determined from the observed luminosity function (LF) using theoretical stellar evolutionary models. Here, we are presenting our initial results related to structure parameters, extinction, distance and mass function of open cluster NGC 6910 based on the deep and wide field mosaic images taken from 1.0m Sampurnand telescope of ARIES, India

A Search for New Open Clusters Hosting Cepheids

2015 ◽  
Vol 24 (4) ◽  
Author(s):  
E. V. Glushkova ◽  
M. V. Zabolotskikh ◽  
A. S. Rastorguev ◽  
A. V. Grudskaya
Keyword(s):  
Star Clusters ◽  
Open Clusters ◽  
Open Star Clusters ◽  
Open Star

AbstractWe analyze yet-unknown genetic links between open star clusters (OSCs) and galactic Cepheids and report the results of the new search for Cepheids – probable OSC members. A sample of 25% of the stars from a new catalog by Berdnikov (published in

The relevance of the Gaia-ESO Survey on the Galactic metallicity gradient: Focus on open clusters

2018 ◽  
Vol 14 (A30) ◽  
pp. 244-245
Author(s):  
Sofia Randich
Keyword(s):  
Star Clusters ◽  
Open Clusters ◽  
Open Star Clusters ◽  
Thin Disc ◽  
Open Star

AbstractAn overview of the Gaia-ESO Survey project is presented, with focus on open star clusters and their use to trace the radial metallicity gradient in the thin disc.

scholarly journals The disintegrating old open cluster Czernik 3

2020 ◽  
Vol 498 (2) ◽  
pp. 2309-2322
Author(s):  
Saurabh Sharma ◽  
Arpan Ghosh ◽  
D K Ojha ◽  
R Pandey ◽  
T Sinha ◽  
...  
Keyword(s):  
Proper Motion ◽  
Near Infrared ◽  
Open Cluster ◽  
Mass Range ◽  
Mass Function ◽  
Optical Telescope ◽  
Motion Data ◽  
Tidal Interactions ◽  
Mass Segregation ◽  
Gaia Dr2

ABSTRACT We have performed a detailed analysis of the Czernik 3 (Cz3) open cluster by using deep near-infrared photometry taken with TIRCAM2 on the 3.6 m Devasthal optical telescope along with the recently available high-quality proper motion data from the Gaia DR2 and deep photometric data from Pan-STARRS1. The cluster has a highly elongated morphology with fractal distribution of stars. The core and cluster radii of the cluster are estimated as 0.5 and 1.2 pc, respectively. We have identified 45 stars as cluster members using the Gaia proper motion data. The distance and age of the cluster are found to be 3.5 ± 0.9 kpc and $0.9^{+0.3}_{-0.1}$ Gyr, respectively. The slope of the mass function `Γ′ in the cluster region, in the mass range ∼0.95 <M/M⊙ < 2.2, is found to be −1.01 ± 0.43. The cluster shows the signatures of mass segregation and is dynamically relaxed (dynamical age = 10 Myr). This along with its small size, big tidal radius, low density/large separation of stars, and elongated and distorted morphology indicates that the Cz3 is a loosely bound disintegrating cluster under the influence of external tidal interactions.

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