Search Publications
Statistical analysis of soft X-ray solar flares during solar cycles 22, 23, and 24
Xiong, Bo; Li, Xiaolin; Wang, Ting +1 more
This paper presents a statistical analysis of soft X-ray flares during the period January 1986 to June 2017 covering the last three solar cycles (SCs) 22, 23, and 24. We have analyzed the distribution of flare number, the relationship between the occurrence rate of soft X-ray flares and solar activity, and the duration of different intensity class…
A study of the Czernik 2 and NGC 7654 open clusters using CCD UBV photometric and Gaia EDR3 data
Paunzen, E.; Bilir, S.; Ak, T. +5 more
We analysed the open clusters Czernik 2 and NGC 7654 using CCD UBV photometric and Gaia Early Data Release 3 (EDR3) photometric and astrometric data. Structural parameters of the two clusters were derived, including the physical sizes of Czernik 2 being
Radioactive isotopes in the interstellar medium
Diehl, Roland
Radioactive components of the interstellar medium provide an entirely-different and new aspect to the studies of the interstellar medium. Injected from sources of nucleosynthesis, unstable nuclei decay along their trajectories. Measurements can occur through characteristic gamma rays that are emitted with the decay, or in cosmic material samples t…
Investigation and application of fitting models for centering algorithms in astrometry
Lin, F. R.; Peng, Q. Y.; Zheng, Z. J. +2 more
To determine the precise positions of stars in CCD frames, various centering algorithms have been proposed for astrometry. The effective point spread function (ePSF) and the Gaussian centering algorithms are two representative centering algorithms. This paper compares in detail and investigates these two centering algorithms in performing data red…
Multi-wavelength analysis of CME-driven shock and Type II solar radio burst band-splitting
Ebenezer, E.; Lata Soni, Shirsh; lal Yadav, Manohar
It is now well established that Coronal Mass Ejections (CMEs) may produce shocks in near Sun and interplanetary medium. A Type-II radio burst is characterized by shock and associated emission with very slow frequency drift rate (∼0.1 MHz/sec). A CME driven shock and their velocity, acceleration/deceleration signature can be observed by a Type-II s…
Radio-loud and radio-quiet CMEs: solar cycle dependency, influence on cosmic ray intensity, and geo-effectiveness
Joshi, Bhuwan; Chandra, Ramesh; Kharayat, Hema
Coronal mass ejections (CMEs) largely influence the space weather and cause geomagnetic perturbations. Hence, the statistical studies pertaining to the occurrence of CMEs over the solar cycles and their consequence at the near-Earth region are extremely important. For an in-depth understanding, such studies need to be carried out considering vario…
Energetic particle distributions in space physics represented by the Pearson differential equation for the kappa distribution
Shizgal, Bernie D.
The kappa distribution has been used for decades as a numerical fitting function to represent the energetic particle distributions measured with satellite instruments. The distributions are generally either a three dimensional distribution in the particle velocity or the one dimensional distribution in a velocity component in a particular directio…
Discovery of deep eclipses in the cataclysmic variable ZTF17aaaeefu (2MASS J00594349+6454419)
Kozhevnikov, V. P.
I performed photometric observations of the cataclysmic variable candidate ZTF17aaaeefu and discovered very deep eclipses. The observations were obtained over 8 nights covering 7 months. The eclipse profile is similar to the eclipse profiles observed in other cataclysmic variables. During the observations, ZTF17aaaeefu showed brightness changes re…
The structure of the IRAS05168+3634 star-forming region
Nikoghosyan, E. H.; Azatyan, N. M.; Andreasyan, D. H. +1 more
This study aims to determine the main physical parameters (N(H2) hydrogen column density and Td dust temperature) of the Interstellar medium, and their distribution in the extended star-forming region, which includes IRAS 05156+3643, 05162+3639, 05168+3634, 05177+3636, and 05184+3635 sources. We also provide a comparative ana…
Study of the open cluster Alessi-Teutsch 9 (ASCC 10) using multiband photometry and Gaia EDR3
Sánchez, Néstor; López-Martínez, Fátima; Ocando, Sandra +1 more
There is a growing interest in the automated characterization of open clusters using data from the Gaia mission. This work evidences the importance of choosing an appropriate sampling radius (the radius of the circular region around the cluster used to extract the data) and the usefulness of additional multiband photometry in order to achieve accu…