arXiv subjects

A. L. Tadross

Publications and source records attributed to A. L. Tadross.

At least 19 recordsLinked to original sources

arXiv2024

Discovered a new open cluster near the poorly studied Majaess 190

We present the results of a comprehensive astrophysical study of a newly discovered open cluster, dubbed Ash-1. Using the third data release of the Gaia space mission, Gaia DR3, Ash-1 was accidentally discovered within the constellation Sagittarius in the field of the poorly studied cluster Majaess 190. Here we present the first estimates of these two clusters' primary astrophysical properties. The membership probabilities P>0.50 were assigned to both clusters using the pyUPMASK technique. The distances were determined using the parallaxes of the clusters' members, which were consistent with the isochrone fitting of the color-magnitude diagrams. The ages and distances of Majaess 190 and Ash-1 are found to be 4 Gyr and 630 Myr; 2130 and 1360 pc, respectively. The extinctions, heliocentric distances, mass function, luminosity function, and overall masses of the studied clusters were also computed. Based on the relaxation times, it appears that both clusters are in a state of dynamic relaxation.

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arXiv2021

Open clusters with proper motions fully separated from the field stars using Gaia DR2

The study of open star clusters makes us understand a lot about the composition and construction of the Milky Way Galaxy. Thanks to the Gaia DR2 database that helps us to get the genetic members of star clusters using their proper motions and parallaxes, estimating their physical properties in a very accurate way. This study aims to detect the reasons that make proper motions value of a cluster is completely separated from the background field stars and not melted in. We studied a large sample of open stellar clusters taken from Dias catalog and drawing the vector point diagrams using the astrometric data of Gaia DR2. Marking the separated clusters and melted ones and study their mean parameters in each galactic quadrant.

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arXiv2021

Gaia astrometric and photometric study of open clusters (Dolidze 18 & Ruprecht 70)

Here, we conducted a photometric and astrometric study of two open stellar clusters Dolidze-18 and Ruprecht-70, which have not been photometrically studied before. The most important thing for using Gaia (DR2) database lies in the positions, parallax, and proper motions, which make us split cluster members from the field ones and get precise astrophysical parameters. On studying the radial density profiles of these clusters, the actual sizes are estimated and found larger using Gaia. From the color-magnitude diagrams and theoretical isochrones, we simultaneously determined the ages, distance moduli, and reddening of the two clusters. However, considering the parallaxes of Gaia (DR2) for the cluster members, we calculated the cluster distance and confirmed what we obtained from the color-magnitude diagram. Then, the Cartesian galactocentric coordinates (Xo, Yo, Zo), and the distances from the galactic center (Rg) were also estimated. According to the luminosity and mass functions, the total luminosity and total mass of the clusters are estimated. Our study shows that Ruprecht-70 is recently dynamically relaxed, while Dolidze 18 is not relaxed yet.

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arXiv2020

Characteristics of the open star cluster Kronberger 60 using Gaia DR2

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 insuffcient astrometric parameters. Improving the observations and analysis methods proved that some of them are not true clusters. The most important aspect of using the Gaia survey lies in the positions, parallax, and proper motions for the cluster stars with the homogeneous photometry, which makes the membership candidates precisely determined. In this respect, several 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.

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arXiv2018

The photometric study of the non-relaxed cluster "Mayer 3"

The astrophysical parameters of the open star cluster Mayer 3 have been estimated using the Newtonian focus (f/4.84) of the 1.88 m Telescope of Kottamia Observatory in Egypt. The VRI observations have been carried out down to a limiting magnitude of V ~ 20 mag. To emphasize the main astrophysical parameters, Near-Infra Red, Two Micron All Sky Survey (2MASS-JHK) database has been used. Analyzing the color-magnitude diagrams and radial density distribution of Mayer 3, the cluster's age, reddening, distance from the Sun, the limited border, core and tidal radii are evaluated. The photometrical membership, the Galactocentric coordinates from the Galactic center and Galactic plane are estimated. Luminosity - mass functions, and the total mass of the cluster are established. Finally, the relaxation time estimation conclude that Mayer 3 is not dynamically relaxed yet.

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arXiv2016

Photometric study of IC 2156

The optical UBVRI photometric analysis has been established using SLOAN DIGITAL SKY SURVEY (SDSS database) in order to estimate the astrophysical parameters of poorly studied open star cluster IC 2156. The results of the present study are compared with a previous one of ours, which relied on the 2MASS JHK infrared photometry. The stellar density distributions and color-magnitude diagrams of the cluster are used to determine the geometrical structure; limited radius, core and tidal radii, the distances from the Sun, from the Galactic plane and from the Galactic center. Also, the main photometric parameters; age, distance modulus, color excesses, membership, total mass, luminosity, mass functions and relaxation time; have been estimated.

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arXiv2014

The Astrophysical Behavior of Open Clusters along the Milky Way Galaxy

The main aim of this paper is to study the astrophysical behavior of open clusters' properties along the Milky Way Galaxy. Near-IR JHK (2MASS) photometry has been used for getting a homogeneous Catalog of 263 open clusters' parameters, which are studied for the first time by the author through the last five years. The correlations between the astrophysical parameters of these clusters have been achieved in morphological way and compared with the most recent works.

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arXiv2014

Axis of Zodiacal light Near Tropic Cancer

The axis of zodiacal lights have been obtained in blue and yellow colors using photoelectric observations of zodiacal light. These observations have been carried out at Abu Simbel Site in Egypt, in October 1975. This site lies too near to the tropic of Cancer, at which the axis of the zodiacal light cone perpendiculars to the horizon. The results show that the plane of the zodiacal light is inclined to the normal by 1.59 degrees in blue color and 1.18 degrees in yellow color. This means that there is a slight variation in zodiacal light axis with wavelength, and the axis almost coincide with the ecliptic. The present results for blue color can be considered as the first one in the world near the tropic of Cancer.

astro-ph.EP↗

arXiv2014

PPMXL photometric study of four open cluster candidates (Ivanov 2, Ivanov 7, Ivanov 9 and Harvard 9)

The astrophysical parameters of four unstudied open star cluster candidates - Harvard 9, Ivanov 2, Ivanov 7, and Ivanov 9 - have been estimated for the first time using the PPMXL database. The stellar density distributions and color-magnitude diagrams for each cluster are used to determine the geometrical structure (cluster center, limited radius, core and tidal radii, the distances from the Sun, from the Galactic center and from the Galactic plane). Also, the main photometric parameters (age, distance modulus, color excesses, membership, total mass, relaxation time, luminosity and mass functions) are estimated.

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arXiv2014

CCD BVRI and 2MASS Photometry of the Poorly Studied Open Cluster NGC 6631

Here we have obtained the {\it BVRI CCD} photometry down to a limiting magnitude of $V \sim$ 20 for the southern poorly studied open cluster NGC 6631. It is observed from the {\it 1.88 m} Telescope of Kottamia Observatory in Egypt. About 3300 stars have been observed in an area of $\sim 10^{\prime} \times 10^{\prime}$ around the cluster center. The main photometric parameters have been estimated and compared with the results that determined for the cluster using {\it JHKs 2MASS} photometric database. The cluster's diameter is estimated to be 10 arcmin; the reddening E(B-V)= 0.68 $\pm$ 0.10 mag, E(J-H)= 0.21 $\pm$ 0.10 mag, the true modulus (m-M)$_{o}$= 12.16 $\pm$ 0.10 mag, which corresponds to a distance of 2700 $\pm$125 pc and age of 500 $\pm$ 50 Myr.

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arXiv2011

PPMXL photometric analysis of three open cluster candidates

We present here the astrophysical parameters of three stellar open cluster candidates using PPMXL1 database. In this study, the main photometric, astrometry and statistical parameters of Ruprecht 13, Ruprecht 16 and Ruprecht 24 are estimated for the first time.

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arXiv2011

Astrophysical parameters of ten poorly studied open star clusters

We present here the fundamental parameters of ten open star clusters, nominated from Kronberger et al. (2006) who presented some new discovered stellar groups on the basis of 2MASS photometry and DSS visual images. Star counts and photometric parameters (radius, membership, distances, color excess, age, luminosity function, mass function, total mass, and the dynamical relaxation time) have been determined for these ten clusters for the first time. In order to calibrate our procedures, the main parameters (distance, age, and color excesses) have been re-estimated for another five clusters, which are studied by Kronberger et al. (2006) as well.

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arXiv2011

First PPMXL photometric analysis of open cluster "Ruprecht 15"

We present here our first series in studying the astrophysical parameters of the open cluster "Ruprecht 15" using PPMXL1 database. In this context, the photometric, astrometry and statistical parameters for this cluster (limited radius, core and tidal radii, distances, membership, reddening, age, luminosity function, mass function, total mass, and the dynamical relaxation time) are determined for the first time.

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arXiv2011

A catalog of 120 NGC open star clusters

A sample of 145 JHK--2MASS observations of NGC open star clusters is studied, of which 132 have never been studied before. Twelve are classified as non-open clusters and 13 are re-estimated self-consistently, after applying the same methods in order to compare and calibrate our reduction procedures. The fundamental and structural parameters of the 120 new open clusters studied here are derived using color-magnitude diagrams of JHK Near-IR photometry with the fitting of solar metallicity isochrones. We provide here, for the first time, a catalog of the main parameters for these 120 open clusters, namely, diameter, distance, reddening and age.

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arXiv2011

Brightness and color of the integrated starlight at celestial, ecliptic and galactic poles

From photoelectric observations of night sky brightness carried out at Abu-Simbel, Asaad et al. (1979) have obtained values of integrated starlight brightness at different Galactic latitudes. These data have been used in the present work to obtain the brightness and color of the integrated starlight at North and South Celestial, Ecliptic and Galactic Poles. The present values of the brightness are expressed in S10 units and mag/arcsec2. Our results have been compared with that obtained by other investigators using photometric and star counts techniques. The B-V and B-R have been calculated and the results are compared with that obtained by other investigators.

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arXiv2011

Taurus stars membership in Pleiades open cluster

In this paper, we study the characteristics and physical properties of the young open cluster Pleiades (NGC 1432; M45; Melotte 22; Seven Sisters) using Near Infra Red, JHK pass bands. Our results have been compared with those found in optical, UBV, newly observations. The membership validity of some variable binary stars, which are Located in Taurus constellation, and their relation with Pleiades cluster have been achieved.

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arXiv2010

Fundamental Parameters of Some New Discovered Open star Clusters

We present here the fundamental properties of some newly discovered open star clusters (Teutsch 144, Alessi 53, Riddle 4 and Juchrt 12) using the JHK Near-IR photometry (2MASS survey) of Cutri et al. (2003). These clusters have been selected from Kronberger et al. (2006) who presented some new discovered stellar groups on the basis of 2MASS photometry and the DSS visual images. The astrometry and photometric parameters are determined using the stellar density distributions and color-magnitude diagrams fittings. Center, radius, membership, distances, reddening, age, luminosity function, mass function, total mass, and the dynamical relaxation time have been estimated for the first time. This paper is a part of Reda's PhD project.

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arXiv2010

The Principal Parameters of Unstudied Open Clusters with NIR Observations

We studied the principal parameters of some previously unstudied open star clusters using the JHK Near-IR photometry (2MASS survey). These clusters have been selected from the updated Catalogs of Dais and Webda. Based on the 2MASS database and the DSS visual images, some homogeneous methods and algorithms have been applied. The astrometry and photometric principal parameters are determined for the first time.

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