Search Publications
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…
Measurements of Sunspot Group Tilt Angles Based on SOHO/MDI and SDO/HMI Magnetograms
Zeng, Xiang-Yun; Zheng, Sheng; Huang, Yao +4 more
The tilt angle of sunspot groups plays a crucial role in solar dynamo models for the generation of the poloidal field, yet the statistical properties of the tilt angle are not fully comprehended. This study employs magnetograms from the Solar and Heliospheric Observatory/Michelson Doppler Imager and Solar Dynamics Observatory/Helioseismic and Magn…
Mid-term Periodicity of Coronal Mass Ejections during the Time Interval 1996–2022
Mei, Ying; Wang, Feng; Deng, Hui +3 more
Coronal mass ejections (CMEs) exhibit a wide range of quasiperiodic variations and are crucial for our understanding of the cyclical evolution of large-scale magnetic fields. However, the mid-term periodicities of different types of CMEs associated with different processes at the source location need to be clearly understood. Based on the CDAW cat…
Parameter Study of Geoeffective Active Regions
Veronig, Astrid; Nedal, Mohamed; Pötzi, Werner +1 more
Geomagnetic storms (GSs) are major disturbances in the terrestrial atmosphere caused by the reconnection process between the incoming plasma ejecta in the solar wind and the planetary magnetosphere. The strongest GSs can lead to auroral displays even at lower latitudes, and cause both satellite and ground-based infrastructure malfunctions. The ear…
Post-AGB candidate IRAS 02143+5852: Cepheid-like variability, three-layer circumstellar dust envelope and spectral features
Rudy, R. J.; Shugarov, S. Yu; Ikonnikova, N. P. +8 more
We present the results of multicolour UBVRCICJHK photometry, spectroscopic analysis and spectral energy distribution (SED) modelling for the post-AGB candidate IRAS 02143+5852. We detected Cepheid-like light variations with the full peak-to-peak amplitude ΔV ~ 0.9 mag and the pulsation period of about 24.9 d. The phased light…
X-ray Analysis of Seyfert 1 Galaxies with Optical Polarization: A Test for Unification Models
Guainazzi, M.; Jiménez-Bailón, E.; Longinotti, A. L. +3 more
In accordance with the AGN Unified Model, observed polarization can be related to the orientation of the line of sight with respect to the torus. AGN X-ray emission arises from the central region and carries the imprints of the obscuring material. We aim to test a unified scheme based on optical polarization using X-ray absorption. Using the XMM-N…
BD+44°493: Chemo-dynamical Analysis and Constraints on Companion Planetary Masses from WIYN/NEID Spectroscopy
Placco, Vinicius M.; Logsdon, Sarah E.; Holmbeck, Erika M. +11 more
In this work, we present high-resolution (R ∼ 100,000), high signal-to-noise ratio (S/N ∼ 800) spectroscopic observations for the well-known, bright, extremely metal-poor, carbon-enhanced star BD+44°493. We determined chemical abundances and upper limits for 17 elements from WIYN/NEID data, complemented with 11 abundances redetermined from Subaru …
A Search for Self-lensing Binaries with TESS and Constraints on their Occurrence Rate
El-Badry, Kareem; Yamaguchi, Natsuko; Sorabella, Nicholas M.
Five self-lensing binaries (SLBs) have been discovered with Kepler light curves. They contain white dwarfs (WDs) in AU-scale orbits that gravitationally lens solar-type companions. Forming SLBs likely requires common envelope evolution when the WD progenitor is an AGB star and has a weakly bound envelope. No SLBs have yet been discovered with data…
Centering algorithm of an unresolved primary and satellite system
Peng, Q. Y.; Guo, B. F.; Hao, J. N.
Affected by the Earth's atmosphere, the image of a primary and satellite system may appear unresolved, such as the dwarf planet Haumea system. It is found by experiments that neither the two-dimensional Gaussian nor modified moment centering algorithms can accurately measure the photocenter of an image of unresolved primary and satellite system ob…
Investigation of a W UMa-type contact binary GZ And in a physical triple system
Zheng, Jie; Jiang, Lin-Qiao
GZ And is a variable star within the visually observed multiple-star system ADS 1693. Recent observations have yielded new light curves for GZ And, obtained using the Xinglong 85-cm telescope and the Transiting Exoplanet Survey Satellite (TESS) satellite. These light curves, along with radial velocity curves, were analyzed simultaneously to ascert…