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 Photometric study of the young open clusters IC 1442, King 21, and Trumpler 7

2020 ◽  
Vol 495 (2) ◽  
pp. 2496-2508 ◽  
Author(s):  
Jayanand Maurya ◽  
Y C Joshi ◽  
A S Gour
Keyword(s):  
Relaxation Time ◽  
Outer Region ◽  
Mass Function ◽  
Open Clusters ◽  
Photometric Study ◽  
Proper Motions ◽  
Dynamical Study ◽  
Data Release ◽  
Solar Metallicity ◽  
Mass Segregation

ABSTRACT We carried out the UBVRcIc photometric study of three poorly studied young open clusters IC 1442, King 21, and Trumpler 7 (Tr 7). We obtained 263, 244, and 128 member stars using Gaia Data Release 2 proper motions and parallaxes in IC 1442, King 21, and Tr 7, respectively. The reddening, E(B − V), was derived to be 0.54 ± 0.04, 0.76 ± 0.06, and 0.38 ± 0.04 mag for these clusters. The comparison of observed colour–magnitude diagrams with solar metallicity isochrones yields log(age) = 7.40 ± 0.30, 7.70 ± 0.20, and 7.85 ± 0.25 yr and corresponding distances of 2847 ± 238, 2622 ± 156, and 1561 ± 74 pc for IC 1442, King 21, and Tr 7, respectively. The estimated mass function (MF) slopes are found to be −1.94 ± 0.18, −1.54 ± 0.32, and −2.31 ± 0.29 for IC 1442, King 21, and Tr 7, respectively. The study of MF slopes done separately in the inner and the outer regions of these clusters gives a steeper slope in the outer region, which suggests spatial variation in slope and mass segregation in the clusters. We found evidence of mass segregation after the dynamical study in these clusters. The obtained relaxation time, TE, is 74, 26, and 34 Myr for the clusters IC 1442, King 21, and Tr 7, respectively. The mass segregation in IC 1442 may be caused by early dynamical relaxation. The estimated TE is well below the ages of King 21 and Tr 7, which indicates that these clusters are dynamically relaxed.

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 A comprehensive study of open clusters Czernik 14, Haffner 14, Haffner 17 and King 10 using multicolour photometry and Gaia DR2 astrometry

2020 ◽  
Vol 494 (1) ◽  
pp. 607-623 ◽  
Author(s):  
D Bisht ◽  
Qingfeng Zhu ◽  
R K S Yadav ◽  
Alok Durgapal ◽  
Geeta Rangwal
Keyword(s):  
Interstellar Extinction ◽  
Mass Function ◽  
Open Clusters ◽  
Circular Path ◽  
Galactic Centre ◽  
Data Sets ◽  
Motion Data ◽  
Solar Metallicity ◽  
Mass Segregation ◽  
Gaia Dr2

ABSTRACT This paper presents an investigation into the four open clusters Czernik 14, Haffner 14, Haffner 17 and King 10, located near the Perseus arm of the Milky Way, using the Gaia DR2, 2MASS, WISE, APASS and Pan-STARRS1 data sets. We find normal interstellar extinction in 12 photometric bands for these clusters. Using Gaia DR2 proper motion data, the numbers of likely cluster members are found to be 225, 353, 350 and 395 for Czernik 14, Haffner 14, Haffner 17 and King 10, respectively. Radii are determined as 3.5, 3.7, 6.2 and 5.7 arcmin for Czernik 14, Haffner 14, Haffner 17 and King 10, respectively. Mean proper motions in RA and Dec. are estimated as (−0.42 ± 0.02, −0.38 ± 0.01), (−1.82 ± 0.009, 1.73 ± 0.008), (−1.17 ± 0.007, 1.88 ± 0.006) and (−2.75 ± 0.008, −2.04 ± 0.006) mas yr−1 for Czernik 14, Haffner 14, Haffner 17 and King 10, respectively. The comparison of observed colour–magnitude diagrams with solar metallicity isochrones leads to ages of 570 ± 60, 320 ± 35, 90 ± 10 and 45 ± 5 Myr for these clusters. The distances of 2.9 ± 0.1, 4.8 ± 0.4, 3.6 ± 0.1 and 3.8 ± 0.1 kpc determined using parallax are similar to the values derived by the isochrone-fitting method. Mass function slopes are found to be in good agreement with the Salpeter value. The total masses are derived as 348, 595, 763 and 1088 M⊙ for Czernik 14, Haffner 14, Haffner 17 and King 10, respectively. Evidence for the existence of a mass-segregation effect is observed in each cluster. Using the Galactic potential model, Galactic orbits are derived for the clusters. It is found that all four clusters follow a circular path around the Galactic Centre.

scholarly journals Development of a Southern Vilnius Standard Photometric System

2021 ◽  
Author(s):  
◽  
Murray Charles Forbes
Keyword(s):  
Local System ◽  
Standard System ◽  
Physical Parameters ◽  
Atmospheric Effects ◽  
Photometric System ◽  
Open Star Clusters ◽  
Cluster Membership ◽  
Open Star ◽  
Solar Metallicity ◽  
The Individual

<p>The Vilnius Standard Photometric System is said to have several advantages over other photometric systems; reduction procedures free of systematic errors, a homogeneous set of standard stars, accurate dereddening, spectral classification and calibration of physical parameters for normal stars, and a good detection rate of abnormal stars. To investigate these, two southern, open star clusters (Omicron Velorum and Kappa Crucis) have been measured in the Vilnius system. The observations were used to derive astrophysical parameters such as age ((45 plus-minus l5)x106 and (10 plus-minus 3)x10 6 years respectively), composition (both solar metallicity), distance to the clusters (m-M = 5m.94 plus-minus 0.02 and 12m.18 plus-minus 0.05), interstellar reddening along our light of sight to the clusters (Ey-v = 0m.00 plus-minus 0.02 and 0m.31 plus-minus 0.09), and cluster membership probabilities for the individual stars. These compared favorably with the consensus of similar analyses made by observers using other photometric systems, with one exception being the distance to Kappa Crucis ( = 11m.59). As no stars further south than declination -26 degrees have been measured in the (original) Vilnius System, it was necessary to calibrate the local system to the standard system by measuring equatorial stars common to both. To alleviate this problem in the future, suitable southern stars were measured to form a southern standard system. Initially bright stars evenly spread across the sky were calibrated - this will ensure any future observing programme will have nearby standards. The next phase of the programme was to calibrate the E-region stars - this is a set of stars in common use as southern standards in other photometric systems. The final phase was to calibrate a sequence of stars near the south celestial pole - producing a set of stars so that the same standards can be observed at any time during the year. This southern standard system could not be completely established in the time available (it is approximately 50% finished), due to the larger than expected uncertainties in the measurements largely caused by the atmospheric effects of the Mount Pinatubo eruption.</p>

Double degenerate candidates in the open cluster NGC 6633

2019 ◽  
Vol 15 (S357) ◽  
pp. 20-23
Author(s):  
Joseph W. Barnett ◽  
Kurtis A. Williams
Keyword(s):  
White Dwarfs ◽  
Binary Star ◽  
Open Cluster ◽  
Star Clusters ◽  
Sequence Evolution ◽  
Total System ◽  
Open Star Clusters ◽  
Low Mass Stars ◽  
Cluster Membership ◽  
Open Star

AbstractThe study of white dwarfs, the end stage of stellar evolution for more than 95% of stars, is critical to bettering our understanding of the late stages of the lives of low mass stars. In particular, the post main sequence evolution of binary star systems is complex, and the identification and analysis of double degenerate systems is a crucial step in constraining models of binary star systems. Binary white dwarfs in open star clusters are particularly useful because cluster parameters such as distance, metal content, and total system age are more tightly constrained than for field double degenerates. Here we use the precision astrometry from the Gaia Data Release 2 catalog to study two other white dwarfs which were identified as candidate double degenerates in the field of the open star cluster NGC 6633. One of the two objects, LAWDS 4, is found to have astrometric properties fully consistent with that of the cluster. In such a case, the object is significantly overluminous for a single white dwarf, strongly indicating binarity. The second candidate binary, LAWDS 7, appears to be inconsistent with cluster membership, though a more thorough analysis is necessary to properly quantify the probability. At present we are proceeding to model the photometric and spectroscopic data for both objects as if they were cluster member double degenerates. Results of this latter analysis are forthcoming. Our results will add crucial data to the study of binary star evolution in open star clusters.

scholarly journals Development of a Southern Vilnius Standard Photometric System

2021 ◽  
Author(s):  
◽  
Murray Charles Forbes
Keyword(s):  
Local System ◽  
Standard System ◽  
Physical Parameters ◽  
Atmospheric Effects ◽  
Photometric System ◽  
Open Star Clusters ◽  
Cluster Membership ◽  
Open Star ◽  
Solar Metallicity ◽  
The Individual

<p>The Vilnius Standard Photometric System is said to have several advantages over other photometric systems; reduction procedures free of systematic errors, a homogeneous set of standard stars, accurate dereddening, spectral classification and calibration of physical parameters for normal stars, and a good detection rate of abnormal stars. To investigate these, two southern, open star clusters (Omicron Velorum and Kappa Crucis) have been measured in the Vilnius system. The observations were used to derive astrophysical parameters such as age ((45 plus-minus l5)x106 and (10 plus-minus 3)x10 6 years respectively), composition (both solar metallicity), distance to the clusters (m-M = 5m.94 plus-minus 0.02 and 12m.18 plus-minus 0.05), interstellar reddening along our light of sight to the clusters (Ey-v = 0m.00 plus-minus 0.02 and 0m.31 plus-minus 0.09), and cluster membership probabilities for the individual stars. These compared favorably with the consensus of similar analyses made by observers using other photometric systems, with one exception being the distance to Kappa Crucis ( = 11m.59). As no stars further south than declination -26 degrees have been measured in the (original) Vilnius System, it was necessary to calibrate the local system to the standard system by measuring equatorial stars common to both. To alleviate this problem in the future, suitable southern stars were measured to form a southern standard system. Initially bright stars evenly spread across the sky were calibrated - this will ensure any future observing programme will have nearby standards. The next phase of the programme was to calibrate the E-region stars - this is a set of stars in common use as southern standards in other photometric systems. The final phase was to calibrate a sequence of stars near the south celestial pole - producing a set of stars so that the same standards can be observed at any time during the year. This southern standard system could not be completely established in the time available (it is approximately 50% finished), due to the larger than expected uncertainties in the measurements largely caused by the atmospheric effects of the Mount Pinatubo eruption.</p>

Dynamical Evolution of Globular Clusters with Mass Spectrum

1991 ◽  
Vol 9 (1) ◽  
pp. 41-44
Author(s):  
Hyung Mok Lee
Keyword(s):  
Mass Spectrum ◽  
Globular Clusters ◽  
Numerical Models ◽  
Relaxation Times ◽  
Dynamical Evolution ◽  
Planck Equation ◽  
Mass Function ◽  
Low Mass Stars ◽  
Wide Range ◽  
Three Body

AbstractWe present a series of numerical models describing the dynamical evolution of globular clusters with a mass spectrum, based on integration of the Fokker-Planck equation. We include three-body binary heating and a steady galactic tidal field. A wide range of initial mass functions is adopted and the evolution of the mass function is examined. The mass function begins to change appreciably during the post-collapse expansion phase due to the selective evaporation of low mass stars through the tidal boundary. One signature of highly evolved clusters is thus the significant flattening of the mass function. The age (in units of the half-mass relaxation time) increases very rapidly beyond about 100 signifying the final stage of cluster disruption. This appears to be consistent with the sharp cut-off of half-mass relaxation times at near 108 years for the Galactic globular clusters.

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.

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.

Sign in / Sign up

Export Citation Format

Share Document