A5021461781- Solar and Space Plasma Dynamics
- Stellar, planetary, and galactic studies
- Solar Radiation and Photovoltaics
- Ionosphere and magnetosphere dynamics
- Complex Systems and Time Series Analysis
- Geomagnetism and Paleomagnetism Studies
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Astrophysics and Star Formation Studies
- Earthquake Detection and Analysis
- Photovoltaic System Optimization Techniques
- Cosmology and Gravitation Theories
- Geophysics and Gravity Measurements
- Dark Matter and Cosmic Phenomena
- Photocathodes and Microchannel Plates
- Fractal and DNA sequence analysis
- Magnetic confinement fusion research
- Adaptive optics and wavefront sensing
- Seismology and Earthquake Studies
- Experimental and Theoretical Physics Studies
- Complex Network Analysis Techniques
- Black Holes and Theoretical Physics
- Statistical Mechanics and Entropy
- Atmospheric Ozone and Climate
University of Zanjan
2015-2024
Research Institute for Astronomy and Astrophysics of Maragh
2019
Institute for Advanced Studies in Basic Sciences
2006-2008
University of Kara
2006
Los Alamos National Laboratory
1996
We present the first results from Transiting Exoplanet Survey Satellite (TESS) on rotational and pulsational variability of magnetic chemically peculiar A-type stars. analyse TESS 2-min cadence data sectors 1 2 a sample 83 Five new rapidly oscillating Ap (roAp) stars are announced. One these pulsates with periods around 4.7 min, making it shortest period roAp star known to date. Four out five multiperiodic. Three singly periodic one show presence mode splitting. Individual frequencies...
Here, we aim to study the statistical properties (i.e., spatial, temporal, and magnetic structures) of extreme ultraviolet coronal bright points (CBPs) observed by SDO during a 4.4 yr period (2010 June 1 2014 October 31). We developed automatic detection method for CBPs based on machine-learning technique Zernike image moments. The average number mean density are estimated be about 572 (per full disk taken at 193 Å) Mm−2, respectively. There is negative correlation (−0.7) between sunspots....
ABSTRACT We present the first asteroseismic results for δ Scuti and γ Doradus stars observed in Sectors 1 2 of TESS mission. utilize 2-min cadence data a sample 117 to classify their behaviour regarding variability place them Hertzsprung–Russell diagram using Gaia DR2 data. Included within our are eponymous members two pulsator classes, SX Phoenicis. Our pulsating intermediate-mass by also allows us confront theoretical models pulsation driving classical instability strip time show that...
ABSTRACT We present the results of a systematic search Transiting Exoplanet Survey Satellite (TESS) 2-min cadence data for new rapidly oscillating Ap (roAp) stars observed during Cycle 2 phase its mission. find seven roAp previously unreported as such and analysis further 25 that are already known. Three show multiperiodic pulsations, while all members rotationally variable stars, leading to almost 70 per cent (22) presented being α2 CVn-type stars. targeted observations known chemically...
Classifying galaxies is an essential step for studying their structures and dynamics. Using GalaxyZoo2 (GZ2) fractions thresholds, we collect 545 11,735 samples in non-galaxy galaxy classes, respectively. We compute the Zernike moments (ZMs) GZ2 images, extracting unique independent characteristics of galaxies. The uniqueness due to orthogonality completeness polynomials, reconstruction original images with minimum errors, invariances (rotation, translation, scaling), different block...
Abstract Classifying galaxies is an essential step for studying their structures and dynamics. Using GalaxyZoo2 (GZ2) fractions thresholds, we collect 545 11,735 samples in nongalaxy galaxy classes, respectively. We compute the Zernike moments (ZMs) GZ2 images, extracting unique independent characteristics of galaxies. The uniqueness due to orthogonality completeness polynomials, reconstruction original images with minimum errors, invariances (rotation, translation, scaling), different block...
Abstract Prediction of solar flares due to the effects on Earth and satellites is an important topic for scientists. We develop a method tool flare prediction by applying support vector machine classifier unique independent Zernike moments extracted from active region (AR) images. In analysis, we used Helioseismic Magnetic Imager (HMI) line-of-sight magnetograms, Atmospheric Imaging Assembly (AIA) ultraviolet (UV at 1600 Å) extreme (EUV 304, 171, 193, 211, 335, 94, 131 images period eight...
ABSTRACT We investigate the relationship between asteroseismic indices and physical quantities of 438 δ Scuti (DSCT) stars observed by Transiting Exoplanet Survey Satellite (TESS) mission at 26 sectors. study scaling relations stellar parameters (effective temperature, surface gravity, density, etc.) such as fundamental frequency, large frequency separation (Δν), highest peak in spectrum, envelope oscillation mode (νmax) for DSCT targets. Using an empirical relation a 2D autocorrelation...
Small-scale extreme-ultraviolet (EUV) dimming often surrounds sites of energy release in the quiet Sun. This paper describes a method for automatic detection these small-scale EUV dimmings using feature-based classifier. The is demonstrated sequences 171 Å images taken by STEREO/Extreme UltraViolet Imager (EUVI) on 2007 June 13 and Solar Dynamics Observatory/Atmospheric Imaging Assembly 2010 August 27. feature identification relies recognizing structure space-time Zernike moments images....
Prediction of solar flares is an important task in physics. The occurrence highly dependent on the structure and topology magnetic fields. A new method for predicting large (M X class) presented, which uses machine learning methods applied to Zernike moments magnetograms observed by Helioseismic Magnetic Imager (HMI) onboard Solar Dynamics Observatory (SDO) a period six years from 2 June 2010 1 August 2016. field images consisting radial component are converted finite sets fed Support Vector...
KIC 10553698A is a hot pulsating subdwarf B (sdB) star observed by the Kepler satellite. It exhibits dipole (l = 1) and quadrupole 2) gravity modes with clear period spacing structure. The seismic properties of provide test stellar evolution models, offer unique opportunity to determine mixing processes. We consider due convective overshooting beyond boundary helium burning core. Very small ( f 10^{-6} ) results in progressive increase size However, moderate 10^{-2} 10^{-5} both lead...
Abstract Low-threshold solid-state detectors with single electron excitation sensitivity can probe nuclear recoil energies in the sub-100 eV range, coinciding typical threshold displacement detector material. We investigate daily and annual modulation of observable event rate for dark matter mass ranging from 0.2 to 5 GeV/c 2 a silicon detector, considering energy direction recoil. The data is obtained molecular dynamics simulation. It shown that directional dependence motion laboratory...
Context. Nanoflares are small impulsive bursts of energy that blend with and possibly make up much the solar background emission. Determining their frequency input is central to understanding heating corona. One method extrapolate distribution larger individually observed flares lower energies. Only if power law exponent greater than 2, it considered possible nanoflares contribute significantly input. Aims. Time sequences ultraviolet line radiances in corona an active region modelled aim...
Abstract Solar flares are an abrupt release of magnetic energy in the Sun’s atmosphere due to reconnection coronal field. This occurs response turbulent flows at photosphere that twist Similar earthquakes, solar represent behavior a complex system, and expectedly their distribution follows power law. We present statistical model based on principle minimum loop undergoing reconnection, which is described as avalanche process. show peaks for flaring events this self-organized critical system...
Aims. We investigate the propagation of torsional waves in coronal structures together with their collimation effects context magnetohydrodynamic (MHD) theory. The interplay equilibrium twist and rotation structure, e.g. jet or tornado, density contrast its internal external media is studied to shed light on nature waves.
We investigate the diurnal modulation of event rate for dark matter scattering on solid targets arising from directionally dependent defect creation threshold energy. In particular, we quantify how this effect would help in separating signal neutrino background. perform a benchmark analysis germanium detector and compute reach experiment is affected by including timing information events. observe that light just above detection magnitude annual enhanced. mass range using either or provides...
Aims. We investigate the standing kink modes of a cylindrical model coronal loops. The density is stratified along loop axis and changes discontinuously at surface cylinder. periods mode profiles are studies with their deviation from those unstratified aim to extract information on scale heights prevailing in solar corona.
Here, we developed a complex network of solar active regions (ARs) to study various local and global properties the network. The values Hurst exponent ($0.8-0.9$) were evaluated by both detrended fluctuation analysis rescaled range applied on time series AR numbers. findings suggest that ARs can be considered as system self-organized criticality. We constructed growing based locations, occurrence times, lifetimes 4,227 recorded from 1 January 1999 14 April 2017. behaviour clustering...
WASP-43 b is one of the most important candidates for detecting an orbital decay. We investigate pieces evidence this expectation as variations in its transit timings, based on ground and space observations. The data set includes observations at TUBITAK National Observatory Turkey Transiting Exoplanet Survey Satellite (TESS). present a global model system, precise photometry from space, ground, archival radial velocity data. Using homogenized modeled light curves, we measure mid-transit...