This work presents BVR photometric observations and analyses for galaxy pair KPG 562 selected from the Karachentsev Catalog of Isolated Pairs of Galaxies. The observations were obtained using the 1.88-m Telescope of the Kottamia Astronomical Observatory (KAO), Egypt. There is no interaction signs assigned for this pair as reported by Karachentsev Catalog.We used the surface photometry technique to obtain photometric parameters for each galaxy of the pair. The isophotal contours, the luminosity profiles, color profiles (B-V, V-R), ellipticity profiles, position angle (PA) profiles and isophotal center-shift (xc, yc) profiles have been presented. The total and absolute magnitude, ellipticity and position angle (PA) were also obtained from the studied galaxy pair.The studied galaxy pair is clearly showing signs of interaction opposed to that found by Karachentsev. We found that the galaxy KPG 562b contains one tidal tail. The length and thickness of tidal tail were obtained and presented in this study.
We present a photometric and astrometric analysis of the NGC 2158 cluster using Gaia DR2 and 2MASS data. The cluster age, color excess, intrinsic distance modulus and distance are calculated to be t = 2.240 ± 0.260 Gyr, E(B − V) = 0.420 ± 0.050 mag, (m − M)⨀ = 12.540 ± 0.130 mag and d⨀ = 3224 ± 200 pc respectively. The photometric analysis and light curve modelling of the proposed eclipsing binary member [NBN2015]78 is performed using the latest version of the Wilson-Devinney (W-D) code. The solutions show that the system is an over-contact binary with a secondary component filling its Roche lobe, with a mass ratio q = 0.262. The primary and the secondary components of the system consist of two late spectral types K1 and K2 respectively. The membership of [NBN2015]78 is discussed using two independent methods, and we find that [NBN2015]78 is an interloper and not a member of NGC 2158.
The estimation of the main parameters of star clusters is a very important target in astrophysical studies. Many of the open clusters listed in known catalogs have insufficient astrometric parameters. Improving the observations and analysis methods proved that some of them are asterisms and not true clusters. The most important aspect of using the Gaia DR2 survey lies in the positions, parallax, and proper motions for the cluster stars with the homogeneous photometry, which makes the membership candidates precisely determined. On this respect, several astor-photometric parameters of the open star cluster Kronberger 60 have been estimated. On studying the radial density profile, the radius is found to be 10.0±0.5 arcmin. It is located at a distance of 1935±90 pc, with an age of 800±50 Myr. Also, the reddening, the luminosity & mass functions, and the total mass of the cluster have been estimated as well. Our study is showing a dynamical relaxation behavior of Kronberger 60.
In this study, we determined the astrophysical parameters of the poorly studied clusters Teutsch 126 and Czernik 11. We used the Visual Red Charge Coupled Device pass‐bands that were carried down to a limiting magnitude of V = 20 mag. The stars of the clusters were observed utilizing the Newtonian focus of a 74‐inch telescope at the Kottamia Astronomical Observatory in Egypt. Cross‐matched data from the new global database Gaia DR2 were used in the present study. The radial density distributions, core and tidal radii, color‐magnitude diagrams, geometrical distances, and ages and color excesses were presented for Teutsch 126 and Czernik 11. The luminosity and mass functions, the total mass and the relaxation time of the two clusters were estimated as well.
Abstract:We present an optical UBVRI photometric analysis of the poorly studied open star cluster IC 2156 using Sloan Digital Sky Survey data in order to estimate its astrophysical properties. We compare these with results from our previous studies that relied on the 2MASS JHK near-infrared photometry. The stellar density distributions and color-magnitude diagrams of the cluster are used to determine its geometrical structure, real radius, core and tidal radii, and its distance from the Sun, the Galactic plane, and the Galactic center. We also estimate, the age, color excesses, reddening-free distance modulus, membership, total mass, luminosity function, mass function, and relaxation time of the cluster.
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