Search Publications
Classification of circular polarization Stokes profiles in a sunspot using k-means clustering
Mathew, Shibu K.; Raja Bayanna, A.; Louis, Rohan Eugene
The magnetic and velocity fields in sunspots are highly structured on small spatial scales which are encoded in the Stokes profiles. The Stokes profiles are in turn, derived from a sequence of polarization modulations on the incoming light that are imaged using an analyser-detector combination. Our aim is to identify Stokes profiles in a sunspot w…
Analysis of global ionospheric scintillation and GPS positioning interference triggered by full-halo CME-driven geomagnetic storm: A case study
Zhao, Dongsheng; Cui, Shuanglei; Zhang, Xueli +7 more
Currently, the 25th solar activity peak has commenced, driving frequent geomagnetic storms and causing irregular disturbances in the global ionosphere, leading to the scintillation of Global Positioning System (GPS) signals, consequently decreasing the accuracy of GPS positioning. Analyzing the patterns of global ionospheric scintillation and chan…
Dampening long-period doppler shift oscillations using deep machine learning techniques in the solar network and internetwork
Tavabi, Ehsan; Sadeghi, Rayhaneh
This study aimed to explore the Doppler shift at different wavelengths in the IRIS solar spectrum and analyze the evolution and statistical properties of longitudinal oscillations with damping in chromosphere and transition region bright points (BPs). Understanding the damping mechanism and statistical properties of oscillations in BPs is crucial …
Towards understanding time variations of proton to helium ratios in the heliosphere: Implication for the time dependence of the elements of the diffusion tensor
Potgieter, M. S.; Aslam, O. P. M.; Ngobeni, M. D.
A comprehensive three-dimensional numerical model for the modulation of cosmic rays in the heliosphere is applied to investigate the relative roles of the time dependence of the elements of the diffusion tensor on the proton to total Helium (p/He) and Helium-3 to Helium-4 (3He2/4He2) ratios at rigidities…
The 24 Aqr triple system: A closer look at its unique high-eccentricity hierarchical architecture
Horch, Elliott P.; Abushattal, Ahmad A.; Al-Wardat, Mashhoor A. +4 more
As its periastron passage occurred during the third quarter of 2020, system 24 Aqr is of particular significance. New visual solutions for the latest speckle interferometry observations collected by the Lowell Discovery Telescope (LTD) with its new QWSSI speckle camera are presented here. A variety of techniques were used to analyze the system, in…
THEMIS observations of compressional Pc5 pulsations in the dawn- and duskside magnetosphere
Sibeck, D. G.; Korotova, G. I.
We present case and statistical studies of compressional Pc5 pulsations observed by the THEMIS spacecraft in the dawn- and duskside magnetosphere from 2007 to 2011. A case study provides evidence for compressional Pc5 pulsations in the dawnside magnetosphere following the arrival of particles injected by a substorm and the subsequent growth of the…
Some observational properties of the Herbig Be Star AS 310
Bakış, Volkan; Alishov, S. A.; Ismailov, Nariman Z. +2 more
The results of spectral and photometric studies of Herbig Be-type star AS 310 have been presented. Photometric observations in the BVRcIc bands performed in 2016-2021 showed that the amplitude of the seasonal brightness variations of the star changes smoothly in different years and reaches a maximum of approximately around Δ V ∼ 0.6 mag in 2018. T…
Type II radio bursts and space weather phenomena: A statistical study
Chandra, Ramesh; Miteva, Rositsa; Koleva, Kostadinka +2 more
In this paper, we present for the first time a comprehensive statistical study between type II radio bursts from the metric (m) to the dekameric–hectometric (DH) domain and their associated solar and space weather (SW) phenomena, namely, solar flares (SFs), sunspot (SN) configurations, filament eruptions, coronal mass ejections (CMEs), their inter…
Dynamical modeling and characteristic analysis of orbits around a comet
He, Yuchen; Wang, Yue; Tian, Lin
As a frontier field of deep-space explorations, the study of comets is of great value to planetary scientific research, resource exploration, and planetary defense. To date, only the ESA's Rosetta spacecraft successfully orbited the comet 67P. The orbital dynamical environment around comets is more complex than that of other small bodies, making t…
Correlations between space weather parameters during intense geomagnetic storms: Analytical study
Miteva, Rositsa; Samwel, Susan
We explore the correlation between different parameters of space weather events associated with intense geomagnetic disturbances that occurred during the solar cycles (SCs) 23 and 24 (1996-2019). The space weather events under this study are the Solar Flares (SFs), Coronal Mass Ejections (CMEs), Geomagnetic Storms (GSs), Solar Energetic Protons (S…