Search Publications
DBSCAN Clustering Algorithm for Detection of Nearby Open Clusters Based on Gaia-DR2
Wang, C.; Xu, S. K.; Zhuang, L. H. +1 more
In this paper, we attempt to use the DBSCAN (Density-Based Spatial Clustering of Applications with Noise) clustering algorithm to detect nearby open clusters based on Gaia Data Release 2 (Gaia-DR2). We select 594284 stars (within a distance of 100 pc to the sun) from the Gaia-DR2 catalog, and construct a five dimensional phase space (three dimensi…
Pseudo-photometric distances of 30 open clusters
Duvert, G.; Chelli, A.
Aims: We demonstrate that reliable photometric distances of stellar clusters, and more generally of stars, can be obtained using pseudomagnitudes and rough spectral type without having to correct for visual absorption.
Methods: We determine the mean absolute pseudomagnitude of all spectral (sub)types between B and K. Distances are comput…
New Carbon Stars in the Catalina Catalog of Periodic Variables
Mauron, N.; Gigoyan, K. K.; Gigoyan, K. S. +5 more
This study is about carbon stars detected in a program of spectral type determinations for a large amount of optically faint periodic variables. These variables are taken from the Catalina Survey Data Release-1 (CSDR1) data set. As much as 967 objects were studied. Spectral classification uses the objective-prism scanned plates of the Hamburg Quas…
Special Section Guest Editorial: The Hitomi X-Ray Observatory, Part 2
Kelley, Richard L.; Nakazawa, Kazuhiro
This guest editorial summarizes the Special Section on the Hitomi X-Ray Observatory.
The first Charge Coupled Device photometry of the poorly studied clusters Teutsch 126 & Czernik 11
Hendy, Yasser; Tadross, Ashraf Latif; Bendary, Reda +1 more
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 Astro…
Probing the nature of AX J0043-737: Not an 87 ms pulsar in the Small Magellanic Cloud
Haberl, F.; Tiengo, A.; Filipović, M. D. +4 more
Aims: AX J0043-737 is a source in the ASCA catalogue whose nature is uncertain. It is most commonly classified as a Crab-like pulsar in the Small Magellanic Cloud (SMC) following apparent detection of pulsations at 87 ms from a single ASCA observation. A follow-up ASCA observation was not able to confirm this, and the X-ray detection of the s…
A photometric study of the nonrelaxed cluster Mayer 3
Tadross, A. L.; Bendary, R.; Hasan, P.
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 Surv…
GT Ursae Majoris AB - a Possible Quadruple System
Kamiński, K.; Dimitrov, W.; Polińska, M. +3 more
We present the first spectroscopic study of an eclipsing system GT UMa. Our spectra show that the main visual component A is a triple-lined star, which consists of a close eclipsing pair and a farther third component. Radial velocity measurements show evidence of reflex motion. We used Hipparcos and our own R-band light curves for the analysis. Th…
Fast stars point to supernovae, black holes
Sokol, Joshua
On 25 April, the European Space Agency released a data set gathered by the Gaia satellite containing the motions, and much more, of 1.3 billion stars. Astronomers have immediately sifted the data for fast-moving stars. They are prized as forensic tools: When rewound, their trajectories point back to the violent events that launched them. Last week…
A review of low-energy transfers
Dutt, Pooja
Low-energy transfers (LET) for lunar and interplanetary missions has received immense attention of the scientific community during the last few decades as its importance was understood by the success of JAXA's Hiten, ESA's SMART-1, NASA's GRAIL and ARTHEMIS missions, and several proposals, like the BepiColombo, Multi-Moon Orbiter and Europa Orbite…