scholarly journals Astrometric and photometric study of the open cluster NGC 2323

2017 ◽  
pp. 59-69 ◽  
Author(s):  
M.Y. Amin ◽  
W.H. Elsanhoury
Keyword(s):  
Total Mass ◽  
Open Cluster ◽  
Dynamical Evolution ◽  
Photometric Data ◽  
Cluster Center ◽  
Photometric Study ◽  
Number Density ◽  
Membership Probability ◽  
Astrometric Data ◽  
Stellar Background

We present a study of the open cluster NGC 2323 using astrometric and photometric data. In our study we used two methods that are able to separate open cluster?s stars from those that belong to the stellar background. Our results of calculations by these two methods indicate that: 1) according to the membership probability, NGC 2323 should contain 497 stars, 2) the cluster center should be at 07h 02m 48.s02 and -08? 20' 17''74,3) the limiting radius of NGC 2323 is 2.31 ? 0.04 pc, the surface number density at this radius is 98.16 stars pc ?2, 4) the magnitude function has a maximum at about mv = 14 mag, 5) the total mass of NGC 2323 is estimated dynamically by using astrometric data to be 890 M_, and statistically by using photometric data to be 900 M_, and 6) the distance and age of the cluster are found to be equal to 900 ? 100 pc, and 140 ? 20 Myr, respectively. Finally the dynamical evolution parameter ? of the cluster is about 436.2.

scholarly journals About the Coma Cluster (Progress Report)

1987 ◽  
Vol 117 ◽  
pp. 112-112
Author(s):  
D. Gerbal ◽  
G. Mathez ◽  
A. Mazure ◽  
E. Salvadore-Solé
Keyword(s):  
Total Mass ◽  
Velocity Dispersion ◽  
Dynamical Evolution ◽  
Dynamical Analysis ◽  
Radial Dependence ◽  
Cluster Center ◽  
Coma Cluster ◽  
Massive Galaxies ◽  
Relaxation Effects ◽  
The Galaxy

The study of the dynamics of the Coma Cluster is of interest for several reasons. First, there exists a great deal of observational information about the cluster, including data on morphology, magnitude, color and redshift for the galaxies, and reasonably detailed x-ray data for the hot gas. Second, the present dynamical state of the cluster is reasonably well-defined. In addition, the segregation of the more luminous (≡ massive) galaxies towards the cluster center shows that two-body relaxation effects are well-advanced (Capelato et al. 1980). The profile of velocity dispersion with radius shows that in the outer parts of the cluster the galaxy velocities are non-isothermal (des Forêts et al. 1984). There is, however, evidence of continuing dynamical evolution. The velocity field of the galaxies at large distances from the center of the cluster suggests continuing infall (Capelato et al. 1982), and two sub-condensations are located in the inner regions (Mazure and Proust 1986). A new dynamical analysis for the cluster is being carried out in two stages. First, a relaxed model with a wide mass spectrum (c.f. Inagaki 1980) is fitted to the data. The contribution of the intergalactic gas is taken into account. With HO = 75 km/sec/Mpc, the total mass within a 3° radius of the center is ∼ 1.5 × 1015 M⊙, of which ∼ 30% is in the intergalactic medium, and M/L ∼ 75 M⊙/L⊙. The ratio of specific energies of the galaxies and the gas is ∼ 1.1, i.e., there is no scale-height problem (these results are described more fully by Gerbal et al. 1986). A second “model independent” analysis using the profiles of the galactic density and velocity dispersion gives the radial dependence of the galactic mass, the gas mass and also gives the total mass, which is found to be ∼ 1.1 × 1015 M⊙ within 3° (Gerbal et al. 1984).

scholarly journals Wide Field Photometric Study of Galactic Cluster NGC 6067

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Alok K. Durgapal ◽  
Geeta Rangwal ◽  
R. K. S. Yadav
Keyword(s):  
Heliocentric Distance ◽  
Open Cluster ◽  
Interstellar Extinction ◽  
Cluster Center ◽  
Wide Field ◽  
Photometric Study ◽  
Galactic Cluster ◽  
Archive Data

We conduct wide field BV photometry of open cluster NGC 6067 using the archive data taken from [email protected] catalogue. The astrophysical parameters of the cluster such as age, cluster center and heliocentric distance using colour magnitude diagrams are calculated. We also calculated the value of interstellar extinction in the direction of this cluster.

scholarly journals Wide Field Photometric Study of Galactic Cluster NGC 6067

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Alok K. Durgapal ◽  
Geeta Rangwal ◽  
R. K. S. Yadav
Keyword(s):  
Heliocentric Distance ◽  
Open Cluster ◽  
Interstellar Extinction ◽  
Cluster Center ◽  
Wide Field ◽  
Photometric Study ◽  
Galactic Cluster ◽  
Archive Data

We conduct wide field BV photometry of open cluster NGC 6067 using the archive data taken from [email protected] catalogue. The astrophysical parameters of the cluster such as age, cluster center and heliocentric distance using colour magnitude diagrams are calculated. We also calculated the value of interstellar extinction in the direction of this cluster.

scholarly journals Shapley supercluster survey: mapping the dark matter distribution

2020 ◽  
Vol 497 (1) ◽  
pp. 52-66
Author(s):  
Yuchi Higuchi ◽  
Nobuhiro Okabe ◽  
Paola Merluzzi ◽  
Christopher Paul Haines ◽  
Giovanni Busarello ◽  
...  
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Total Mass ◽  
Dynamical Evolution ◽  
Number Density ◽  
Matter Distribution ◽  
X Ray ◽  
The Core ◽  
Dark Matter Distribution ◽  
The Masses

ABSTRACT We present a 23 deg2 weak gravitational lensing survey of the Shapley supercluster core and its surroundings using gri VST images as part of the Shapley Supercluster Survey (ShaSS). This study reveals the overall matter distribution over a region containing 11 clusters at z ∼ 0.048 that are all interconnected, as well as several ongoing cluster–cluster interactions. Galaxy shapes have been measured by using the Kaiser–Squires–Broadhurst method for the g- and r-band images and background galaxies were selected via the gri colour–colour diagram. This technique has allowed us to detect all of the clusters, either in the g- or r-band images, although at different σ levels, indicating that the underlying dark matter distribution is tightly correlated with the number density of the member galaxies. The deeper r-band images have traced the five interacting clusters in the supercluster core as a single coherent structure, confirmed the presence of a filament extending North from the core, and have revealed a background cluster at z ∼ 0.17. We have measured the masses of the four richest clusters (A3556, A3558, A3560, and A3562) in the two-dimensional shear pattern, assuming a spherical Navarro–Frenk–White profile and obtaining a total mass of $\mathcal {M}_{\rm ShaSS,WL}{=}1.56^{+0.81}_{-0.55}{\times }10^{15\, }{\rm M}_{\odot }$, which is consistent with dynamical and X-ray studies. Our analysis provides further evidence of the ongoing dynamical evolution in the ShaSS region.

scholarly journals Photometric analysis of newly discovered open clusters SAI 24 and SAI 94 based on PPMXL catalogue

2019 ◽  
pp. 45-53
Author(s):  
W.H. Elsanhoury ◽  
Magdy Amin
Keyword(s):  
Galactic Plane ◽  
Open Cluster ◽  
Dynamical Evolution ◽  
Open Clusters ◽  
Cluster Center ◽  
Crossing Time ◽  
Magnitude Diagram ◽  
The Masses ◽  
Mass Functions ◽  
Projected Distance

In our present work, we studied the photometric characteristics (core radius, limiting radius, reddening... etc.) as well as their dynamical state of the two newly discovered open clusters, SAI 24 and SAI 94. We investigated their photometric properties in the J, H, and Ks bands with the PPMXL catalogue. A method of separating open cluster stars from those belonging to the stellar background has been employed. The results of our calculations indicate that the numbers of probable members in SAI 24 and SAI 94 are 202 and 199, respectively. We have estimated the cluster center for SAI 24, i.e. ?2000 = 02h 59m 26 .s36 and ?2000 = 60? 33' 02.''50 and for SAI 94 is ?2000 = 08h 10m 16 .s36, ?2000 = ?46? 17' 07.''91. The core radii rcore for SAI 24 and SAI 94 are found to be (1.92 ? 0.38) arcmin and (1.22 ? 0.10) arcmin, respectively and in the same manner the limiting radii rlim are about (2.45 ? 0.64) and (3.07 ? 0.57) arcmin. From the color-magnitude diagram, in view of the approximate logarithmic ages for SAI 24 and SAI 94 of 7.20 ? 0.20 and 9.10 ? 0.05, their distances are estimated to be (930 ? 30) pc and (3515 ? 60) pc, respectively. Also, we have calculated their projected distances (X? and Y?) to the Galactic plane and the projected distance Z? from the Galactic plane. The luminosity and mass functions of SAI 24 and SAI 94 clusters were outlined; accordingly, the masses were calculated to be (285 ? 17) M? and (317 ? 18) M?, respectively. Finally, we concluded that these two clusters are dynamically relaxed according to our estimation of their dynamical evolution parameter ? as a function of their crossing time Tcross. The evaporation time ?ev as a function of their relaxation time Trelax is about 6.18 Myr and 25.38 Myr for SAI 24 and SAI 94, respectively.

scholarly journals The Bologna Open Cluster Chemical Evolution project: a large, homogeneous sample of Galactic open clusters

2008 ◽  
Vol 4 (S258) ◽  
pp. 153-160
Author(s):  
Angela Bragaglia
Keyword(s):  
Chemical Evolution ◽  
Galactic Disk ◽  
Open Cluster ◽  
Open Clusters ◽  
Photometric Data ◽  
Homogeneous Sample ◽  
Metallicity Distribution

AbstractThe Bologna Open Cluster Chemical Evolution (BOCCE) project is a photometric and spectroscopic survey of open clusters, to be used as tracers of the Galactic disk properties and evolution. The clusters parameters (age, distance, reddening, metallicity, and detailed abundances) are derived in a precise and homogeneous way. This will contribute to a solid, reliable description of the disk: the clusters parameters will be used, for instance, to determine the metallicity distribution in the Galactic disk and how it has evolved with time. We have concentrated on old open clusters and we have presently in our hands data for about 40 open clusters; we have fully analyzed the photometric data for about one half of them and the spectra for one quarter of them.

scholarly journals Global estimates of plasmaspheric losses during moderate disturbance intervals

2010 ◽  
Vol 28 (1) ◽  
pp. 27-36 ◽  
Author(s):  
M. Spasojevic ◽  
B. R. Sandel
Keyword(s):  
Solar Wind ◽  
Electric Field ◽  
Boundary Layers ◽  
Total Mass ◽  
Density Ratio ◽  
Individual Case ◽  
Number Density ◽  
Inner Magnetosphere ◽  
Moderate Disturbance ◽  
Global Estimates

Abstract. For a set of five moderate disturbance events, we calculate the total number of He+ ions removed the plasmasphere using calibrated global EUV images. In each of the events, between ~0.6 and 2.2×1030 He+ ions are removed from a region of the inner magnetosphere from L=1.5 to 5.5. This loss constitutes between 20% and 42% of the initial He+ distribution. The lost percentage is correlated with the number of hours of strongly positive solar wind electric field (Ey>2.5 mV/m). Also, the total amount of material removed from the plasmasphere is estimated by using several values of the He+ to H+ number density ratio. The total mass lost is found to be in the range of 20 to 80 metric tons although for each individual case the estimate can vary by over 50% depending on assumed density ratio. We also attempt to distinguish between losses to the ionosphere and losses to the dayside boundary layers by estimating losses interior and exterior to the newly formed plasmapause boundary. For the events studied, losses inside the new plasmapause constitute between 24% to 54% of the total number of He+ ions lost.

scholarly journals STUDY OF AN INTERMEDIATE AGE OPEN CLUSTER IC 1434 USING GROUND-BASED IMAGING AND GAIA DR2 ASTROMETRY

2021 ◽  
Vol 57 (2) ◽  
pp. 381-389
Author(s):  
Y. H. M. Hendy ◽  
D. Bisht
Keyword(s):  
Radial Distribution ◽  
Proper Motion ◽  
Open Cluster ◽  
Membership Probability ◽  
Kinematical Analysis ◽  
The Mean ◽  
First Time ◽  
Right Ascension ◽  
Cluster Age ◽  
Gaia Dr2

We present a detailed photometric and kinematical analysis of the poorly studied open cluster IC 1434 using CCD VRI, APASS, and Gaia DR2 database for the first time. By determining the membership probability of stars we identify the 238 most probable members with a probability higher than 60%; by using proper motion and parallax data as taken from the Gaia DR2 catalog. The mean proper motion of the cluster is obtained as μx=−3.89±0.19 and μy=−3.34±0.19 mas yr−1 in both the directions of right ascension and declination. The radial distribution of member stars provides the cluster extent as 7.6 arcmin. We estimate the interstellar reddening E(B−V) as 0.34 mag using the transformation equations from the literature. We obtain the values of cluster age and distance as 631±73 Myr and 3.2±0.1 kpc.

scholarly journals Open cluster remnants in low-density Galactic fields

2009 ◽  
Vol 5 (S266) ◽  
pp. 487-490
Author(s):  
D. B. Pavani ◽  
L. O. Kerber ◽  
E. Bica ◽  
W. J. Maciel
Keyword(s):  
Galactic Disk ◽  
Information Source ◽  
Open Cluster ◽  
Dynamical Evolution ◽  
Theoretical Models ◽  
Open Clusters ◽  
Low Density ◽  
Statistical Tool ◽  
General Picture ◽  
Disk Evolution

AbstractOpen cluster remnants (OCRs) are fundamental objects to investigate open cluster dissolution processes (e.g., Bica et al. 2001; Carraro 2002; Pavani et al. 2003; Carraro et al. 2007; Pavani & Bica 2007). They are defined as poorly populated concentrations of stars, with enough members to show evolutionary sequences in colour–magnitude diagrams (CMDs) as a result of the dynamical evolution of an initially more massive physical system. An OCR is intrinsically poorly populated, which makes its differentiation from field-star fluctuations difficult. Among the possible approaches to establish the nature of OCRs, we adopted CMD analysis combined with a robust statistical tool applied to 2mass data. In addition, photometry is the main information source available for possible OCRs (POCRs). We developed a statistical diagnostic tool to analyse the CMDs of POCRs and verify them as physical systems, explore membership probabilityies taking into account field contamination and derive age, distance and reddening values in a self-consistent way. We present the results of our analysis of 88 POCRs that are part of a larger sample that is widely distributed across the sky, with a significant density contrast of bright stars compared to the Galactic field. The 88 objects are projected onto low-density Galactic fields, at relatively high latitudes (|b| > 15°). Studies of larger POCR samples will provide a better understanding of OCR properties and constraints for theoretical models, including new insights into the evolution of open clusters and their dissolution rates. The results of this ongoing survey will provide a general picture of these fossil stellar systems and their connection to Galactic-disk evolution.

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