Article
Astronomy & Astrophysics
I. O. I. Virtanen, A. A. Pevtsov, I. I. Virtanen, K. Mursula
Summary: Researchers constructed additional active regions and applied them to the far-side of the Sun in an SFT simulation to assess the possible effects and the magnitude of error that the missing far-side flux causes. The results showed that adding active regions with short lifetimes to the far-side of the Sun results in significantly stronger polar fields in minimum times and slightly delayed polarity reversals.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
I. Tahtinen, I. I. Virtanen, A. A. Pevtsov, K. Mursula
Summary: By studying the relationship between photospheric magnetic fields and ultraviolet radiation, we found that the percentage of bright pixels can explain the variability of 1600 angstrom emission. We developed a model to predict the size of the photospheric magnetic field and found a close correspondence between the magnetic field and bright and dark clusters.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
I. I. Yakovkin, V. G. Lozitsky
Summary: We reviewed our previous results on this topic by expanding the wavelength range and analyzing a greater volume of observational data, including an X limb flare. By examining the active prominence and the limb flare, we found reliable and oppositely polarized secondary peaks in the V parameter. The observed spectral features suggest the presence of magnetic splitting and Doppler shift, with a magnetic field of approximately 2.2x10(5) G and a radial velocity of -46 km/s. However, alternative explanations involving weaker magnetic fields and significant macroscopic velocities were also considered.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
G. J. M. Vissers, S. Danilovic, X. Zhu, J. Leenaarts, C. J. Diaz Baso, J. M. da Silva Santos, J. de la Cruz Rodriguez, T. Wiegelmann
Summary: This study compares the similarity between the chromospheric magnetic field inferred from observations and the field obtained from a magnetohydrostatic extrapolation based on a high-resolution photospheric magnetogram. The results show that the extrapolated field underestimates the amount of structure and the strength of the transverse field.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
X. Zhu, T. Wiegelmann
Summary: The aim of this study is to develop a fast and consistent extrapolation method for modeling multiple layers of the solar atmosphere. The new approach combines the magnetohydrostatic extrapolation with the nonlinear force-free field extrapolation, resulting in accurate and efficient reconstruction of the magnetic fields.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
H. Ebadi, S. Shahmorad, S. Vasheghani Farahani
Summary: The research aims to model torsional waves in twisted flux tubes of solar coronal magnetic plasma structures, using force-free conditions to determine equilibrium magnetic fields and study the effects of magnetic twist parameter on torsional waves. Through numerical calculations and variable separation techniques, magnetic field characteristics and frequency dependence of torsional waves are obtained, revealing an increase in the omega(2)/omega(1) ratio with the twist parameter at a fixed distance.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
R. J. Campbell, M. Mathioudakis, M. Collados, P. H. Keys, A. Asensio Ramos, C. J. Nelson, D. Kuridze, A. Reid
Summary: The study reveals the presence of ubiquitous small-scale transverse magnetic fields in the quiet Sun internetwork region, which exhibit complex structures. High-resolution observations and magnetic inversion techniques can be used to characterize and track the dynamic evolution of these small-scale magnetic features.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Xianyong Bai, Hui Liu, Yuanyong Deng, Jie Jiang, Jingjing Guo, Yi Bi, Tao Feng, Zhenyu Jin, Wenda Cao, Jiangtao Su, Kaifan Ji
Summary: This study proposes a new method to estimate the magnetic field components from photospheric continuum images using deep convolutional neural networks. Experimental results show that the method can successfully estimate the magnetic field in different regions of the Sun, providing quick and accurate magnetic field information.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
X. J. Zhang, L. H. Deng, Y. Fei, C. Li, X. A. Tian, Z. J. Wan
Summary: Hemispheric asymmetry of solar magnetic structures is an important feature of solar cycles. A long-term study using data from the National Astronomical Observatory of Japan reveals a correlation between the sunspot relative numbers and international sunspot numbers, suggesting periodic variations in hemispheric asymmetry. The findings provide insights into the mechanism responsible for the generation and variation of hemispheric coupling in the Sun.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Review
Astronomy & Astrophysics
Yuhong Fan
Summary: This article reviews the origin of solar active regions on the surface, emphasizing on how the toroidal magnetic field can lead to the formation of these regions. It also discusses the new results from global simulations, near-surface layer simulations, and helioseismic investigations that challenge the traditional understanding of active region formation.
LIVING REVIEWS IN SOLAR PHYSICS
(2021)
Article
Astronomy & Astrophysics
T. Mehta, K. Jain, S. C. Tripathy, R. Kiefer, D. Kolotkov, A-M Broomhall
Summary: In this study, we investigated the relationship between the solar cycle and the presence and periodicity of the Quasi-Biennial Oscillation (QBO). Using helioseismic techniques and solar activity proxies, we found that the presence of the QBO varied significantly between solar cycles. The QBO presence was reduced in Cycle 24 compared to Cycle 23, and it was not dependent on the depth or frequency of the p-mode.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Bogyeong Kim, Yu Yi
Summary: The remote sensing technique of measuring the magnetic field on sunspots was applied by Hale (1908), while Babcock (1961) showed that the solar surface magnetic field is a dipole in first-order approximation and reverses every solar cycle. The Wilcox Solar Observatory (WSO) provides the spherical harmonics coefficients for the solar corona magnetic field, and based on the photospheric magnetic field data, we calculate the multipole components of the solar magnetic field. The results reveal that the axis-symmetric fields of the dipole and octupole are the prominent cycle components over the last 4 solar activity cycles, indicating that the current inversion driving the solar magnetic field reversal originates from the equatorial region and spreads globally.
JOURNAL OF THE KOREAN ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Emilia Capozzi, Ernest Alsina Ballester, Luca Belluzzi, Javier Trujillo Bueno
Summary: The linear polarization angle in the scattering polarization wings of resonance lines can provide valuable information for diagnosing unresolved magnetic fields. It is sensitive not only to the flux of the photospheric magnetic field, but also to the fraction of the resolution element that the magnetic field occupies.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
A. Adrover-Gonzalez, J. Terradas, R. Oliver, M. Carbonell
Summary: This study comprehensively investigates the gravitational stability of prominence threads using a basic hydrodynamic model, finding that stable and unstable equilibrium solutions are possible depending on various factors such as initial position, density contrast, length, and total length of magnetic field lines. The results of this study provide new insights into the behavior of threads in curved magnetic fields under the influence of gravity and can help interpret more complex numerical simulations.
ASTRONOMY & ASTROPHYSICS
(2021)
Review
Astronomy & Astrophysics
Baolin Tan
Summary: Measuring magnetic fields in the upper solar atmosphere is a challenge, and radio observations are a feasible approach. Previous studies only provided implicit diagnostic functions, but this work collects and organizes explicit diagnostic methods for diagnosing coronal magnetic fields. These methods can cover all regions of the solar chromosphere and corona and help derive magnetic fields using broadband spectral solar radio imaging observations. This is important for studying solar activities and predicting space weather events.
RESEARCH IN ASTRONOMY AND ASTROPHYSICS
(2022)
