Article
Astronomy & Astrophysics
Anitha Ravishankar, Grzegorz Michalek
Summary: The study analyzed 38 non-interacting halo and partial halo CMEs parameters in STEREO/SECCHI images, and investigated their correlation with the generation of SEPs.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Abd-ur Raheem, Huseyin Cavus, Gani Caglar Coban, Ahmet Cumhur Kinaci, Haimin Wang, Jason T. L. Wang
Summary: This study identified the source active regions for the majority of CMEs using a filtration process and machine learning to compare the physical parameters of sunspot groups with properties of CMEs to uncover the mechanisms behind CME initiation. The neural network successfully identified source HARPs for 4895 out of 14604 CMEs recorded from 2011 to 2020, showing the effectiveness of the method in source region identification.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
X. J. Zhang, L. H. Deng, Z. P. Qiang, Y. Fei, X. A. Tian, C. Li
Summary: This research investigates the hemispheric asymmetry of coronal mass ejections (CMEs) between 1996 and 2020, and finds that the hemispheric asymmetry of CMEs is mainly caused by specific CMEs rather than regular CMEs. The hemispheric asymmetry of high-latitude CMEs appears to have little connection to that of low-latitude CMEs. The dominant hemisphere, cumulative trend, and amplitude of CMEs vary between different solar cycles.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
S. W. Good, L. M. Hatakka, M. Ala-Lahti, J. E. Soljento, A. Osmane, E. K. J. Kilpua
Summary: Interplanetary coronal mass ejections (ICMEs) exhibit fluctuations in magnetic field and velocity at different scales, with the cross helicity serving as a measure of the balance between these fluctuations. Observations show that ICME flux ropes and sheaths at 1 au have varying levels of cross helicity, suggesting dynamic equilibrium influenced by solar activity.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
K. Martinic, M. Dumbovic, M. Temmer, A. Veronig, B. Vrsnak
Summary: This study investigates different methods for determining the orientation of coronal mass ejections (CMEs) in the near-Sun environment and explores the non-radial flow in the sheath region of interplanetary CMEs (ICMEs). The results show that current methods are limited in accurately determining the orientation of CMEs, but most CMEs have a low inclination. Consistent estimations of the tilt between remote and in situ data were obtained for the majority of CME-ICME pairs. The observed non-radial flows suggest that the CME orientation may impact its propagation.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Beili Ying, Li Feng, Bernd Inhester, Marilena Mierla, Weiqun Gan, Lei Lu, Shuting Li
Summary: This study investigates the formation mechanism of a shock driven by an aspherical CME and demonstrates the impact of the difference in CME's principal radius of curvature on the estimation of shock and coronal parameters. By using three-dimensional reconstructions, the researchers were able to derive corona parameters at high latitudes and analyze the bow-shock formation mechanism.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
L. Rodriguez-Garcia, T. Nieves-Chinchilla, R. Gomez-Herrero, I. Zouganelis, A. Vourlidas, L. A. Balmaceda, M. Dumbovic, L. K. Jian, L. Mays, F. Carcaboso, L. F. G. dos Santos, J. Rodriguez-Pacheco
Summary: The main objective of this study is to investigate the radial and longitudinal evolution of the interplanetary counterpart (ICME) in the inner heliosphere and to examine the different magnetic flux-rope configurations observed on the solar disk and in situ at various locations.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Q. M. Zhang
Summary: This paper aims to track the three-dimensional evolution of a full halo coronal mass ejection (CME) and uses a revised cone model to derive its morphological and kinematic properties. The results show that the revised cone model fits nicely with the observed CME and the CME exhibits changes in angle and distance over time.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Alexander W. James, David R. Williams, Jennifer O'Kane
Summary: This study aims to quantify the variation of critical height for torus instability-driven CMEs over time in solar active regions, and finds that the rate of CMEs is significantly higher when the critical height is increasing during phases of magnetic flux increase. Additionally, the critical height is generally proportional to the separation of magnetic polarities in the active regions.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Multidisciplinary Sciences
Alessandro Bemporad
Summary: Due to the lack of UV-EUV observations of CMEs far from the Sun, our understanding of the thermodynamic evolution of these solar phenomena is limited. This study analyzed a slow CME observed in visible and UV light and used the data to determine the distribution of plasma electron density, temperature, and thermal energy. The results showed that the CME core had higher temperatures compared to the surrounding void and front, and the core temperatures increased during the CME expansion, indicating plasma heating processes. The distribution of thermal energy also exhibited asymmetry, possibly due to interaction with nearby coronal structures. This work demonstrates the potential of combining UV and visible light data and future multi-slit spectroscopic observations of CMEs.
Article
Astronomy & Astrophysics
D. Sudar, B. Vrsnak, M. Dumbovic, M. Temmer, J. Calogovic
Summary: The study reveals that under isotropic solar wind conditions, the distance between the apex and the flank of a CME increases monotonically with time, but never becomes fully circular. The velocity of the leading edge segments converges towards the solar wind speed, while the flank speed does not exceed that of the apex.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
O. Chang, R. F. Gonzalez, M. M. Bisi, R. A. Fallows
Summary: IPS observations provide valuable information about solar wind conditions and density irregularities, but interpreting complex structures can be challenging due to the changing physical properties of plasma with distance from the Sun. Numerical simulations can help compare CME structure and physical changes, shedding light on the complexity of IPS observations.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
D. E. Morosan, A. Kumari, E. K. J. Kilpua, A. Hamini
Summary: The study conducted a statistical analysis of 64 moving bursts to determine how often CMEs are accompanied by moving radio bursts. The majority of moving radio sources are found to be associated with CMEs and wide CMEs, suggesting strong lateral expansion during the early stages of the eruption plays a key role in radio emission occurrence.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
D. E. Morosan, J. Pomoell, A. Kumari, R. Vainio, E. K. J. Kilpua
Summary: This study investigates the early acceleration location, escape, and propagation directions of electron beams associated with herrinbgone bursts during the early evolution of a strongly expanding CME-driven shock wave. By combining ground-based radio observations and space-based extreme-ultraviolet and white-light observations, the researchers were able to produce a three-dimensional representation of the electron acceleration locations and investigate the origin of the observed bursts.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
C. Scolini, S. Dasso, L. Rodriguez, A. N. Zhukov, S. Poedts
Summary: Coronal mass ejections (CMEs) are large-scale eruptions from the Sun into interplanetary space, influencing space weather. The EUropean Heliospheric FORecasting Information Asset (EUHFORIA) model shows consistent descriptions of solar wind and CME radial evolution. However, improvements are necessary for better replication of the CME radial extension.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
M. Terres, Gang Li
Summary: In this study, the nature of the spectral break in solar wind turbulence is examined using magnetic field data from the MESSENGER spacecraft during four planetary flybys at different distances from the Sun. The study identifies spectral breaks and spectral bumps and finds that the frequency of the spectral bump is independent of the ratio of the spectral break frequency. This suggests a common dependence on the magnetic field strength for both the spectral break wavenumber and the spectral bump frequency.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
N. H. Bian, Gang Li
Summary: This study presents a model for the transport of solar energetic particles along stochastic Parker spirals in the inner heliosphere. The model takes into account the effects of pitch angle scattering and magnetic focusing in the interplanetary medium. The heliolongitudinal distribution of particles propagating along stochastic Parker spirals is found to follow a wrapped Gaussian distribution or a von Mises distribution.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Yuming Wang, Jingnan Guo, Gang Li, Elias Roussos, Junwei Zhao
Summary: Research has found that the intensity of galactic cosmic rays (GCRs) is modulated by solar activity, with a lag behind the variation in sunspot number (SSN). The study has also revealed that the opening of the solar magnetic field lags behind SSN before the solar wind arrives. Furthermore, low latitude regions contribute significantly to the total open magnetic flux.
ASTROPHYSICAL JOURNAL
(2022)
Article
Geosciences, Multidisciplinary
Xing Meng, Michela Ravanelli, Attila Komjathy, Olga P. Verkhoglyadova
Summary: The Mw8.3 Illapel earthquake induced ionospheric disturbances, with stronger disturbances observed above the northern region of the epicenter than above the southern region. Modeling results show that 31% of the north-south asymmetry in disturbance magnitude is caused by different ground motion strengths, while the remaining 69% is attributed to the background ionospheric state.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Multidisciplinary Sciences
Junxiang Hu, Vladimir S. Airapetian, Gang Li, Gary Zank, Meng Jin
Summary: The discovery of frequent superflares on active cool stars is crucial in understanding the properties of eruptive events and their impact on exoplanetary environments. Research suggests that solar and young solar-like stars' flares can produce high-energy particle events that influence the atmospheric biosignatures of exoplanets and the chemistry and isotopic composition of circumstellar disks.
Article
Astronomy & Astrophysics
A. Santa Fe Duenas, R. W. Ebert, M. A. Dayeh, M. Desai, L. K. Jian, G. Li, C. W. Smith
Summary: We examined the variations in heavy ion peak intensities and energy spectra of energetic storm particles (ESP) at CME-driven interplanetary shocks. The observations showed dependence on heliolongitude relative to the source region of their associated CMEs and CME speed. We found that the organization of ESP events at 1 au is influenced by the longitude of their CME solar source and the speed of the CME. The observations also revealed that high-speed events have larger angular extension and heavier ion peak intensities near the nose of the shock. The study emphasizes the significance of spacecraft position relative to CME source longitude and CME speed in understanding the properties of ESP events at 1 au.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Y. D. Xu, G. Li, S. Yao
Summary: We investigate spectral hardening in solar flares using numerical simulations and find that it is influenced by the width and Peclet number of the shock. Two different Monte Carlo simulation methods are applied, and the results agree well with each other and with analytical results.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Shuai Fu, Zheyi Ding, Yongjie Zhang, Xiaoping Zhang, Cunhui Li, Gang Li, Shuwen Tang, Haiyan Zhang, Yi Xu, Yuming Wang, Jingnan Guo, Lingling Zhao, Yi Wang, Xiangyu Hu, Pengwei Luo, Zhiyu Sun, Yuhong Yu, Lianghai Xie
Summary: This article reports the first measurements of a widespread Solar Energetic Particle (SEP) event during the transit period to Mars by China's Tianwen-1 mission. The measurements show that the double-power-law spectrum and radial dependence of SEP peak intensities are similar to those observed by near-Earth spacecraft. The time-intensity profiles at different locations also indicate the reservoir effect, suggesting that the double-power-law spectrum is likely generated at the acceleration site and cross-field diffusion is crucial for the formation of the SEP reservoir phenomenon.
ASTROPHYSICAL JOURNAL LETTERS
(2022)
Article
Astronomy & Astrophysics
S. T. Hart, M. A. Dayeh, R. Bucik, M. Desai, R. W. Ebert, G. C. Ho, G. Li, G. M. Mason
Summary: In this study, using ion measurements from spacecraft observations, we identified 854 time periods rich in He-3 between 1997 and 2021. We found a clear correlation in the abundance ratios of He-3/He-4 and Fe/O, and provided a live catalog of these time periods for public use.
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2022)
Article
Astronomy & Astrophysics
Gang Li, Albert Y. Y. Shih, Robert C. C. Allen, George C. C. Ho, Christina M. S. Cohen, Mihir Desai, Maher A. A. Dayeh, Glenn M. M. Mason
Summary: We investigate the production and propagation of energetic neutral atoms (ENAs) in solar flares and coronal mass ejection (CME)-driven shocks. By calculating the time profiles and fluence spectra of solar ENAs at 1 au, we find significant differences between ENAs produced downstream at CME-driven shocks and ENAs produced at large-scale post-flare loops in solar flares. Our calculations suggest that solar ENAs can be used as a new tool to study the acceleration process of solar energetic particles (SEPs) and to differentiate between the acceleration sites in large SEP events, namely the large loops in solar flares and downstream of CME-driven shocks.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Gang Li, N. H. Bian
Summary: In this study, Leighton's diffusion model is extended to describe the turbulent mixing of magnetic footpoints on the solar wind source surface using the spherical Ornstein-Uhlenbeck process. The Lagrangian velocity and positions of magnetic footpoints are obtained numerically from a set of stochastic differential equations. Unlike the magnetic field lines driven by standard Brownian processes, the interplanetary magnetic field lines in our model are smooth differentiable functions with finite path lengths. The path-length distributions of these boundary-driven interplanetary magnetic field lines and their dependency on controlling parameters are investigated.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Xiangyu Wu, Gang Li, Lulu Zhao, Frederic Effenberger, Linghua Wang, Shuo Yao
Summary: Using the fraction velocity dispersion analysis method, this study investigates the release time and energy dependence of near-relativistic electrons in impulsive solar energetic electron events. The results show delayed release times for outward-propagating electrons compared to downward-propagating electrons, and clear energy dependence in most of the events. The implications of this energy-dependent release on the Magnetohydrodynamics turbulence property at the electron acceleration site are discussed.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
N. Wijsen, G. Li, Z. Ding, D. Lario, S. Poedts, R. J. Filwett, R. C. Allen, M. A. Dayeh
Summary: Particles measured in large gradual solar energetic particle events are predominantly accelerated at shocks driven by coronal mass ejections (CMEs). The origin of the seed particle population is not the bulk solar wind thermal material, but rather a suprathermal population present in the solar wind. The distribution of this suprathermal particle population is influenced by the background solar wind configuration and cross-field diffusion.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
K. Moreland, M. A. Dayeh, G. Li, A. Farahat, R. W. Ebert, M. I. Desai
Summary: In this study, the effect of different sampling windows on the properties of shocks and energetic storm particles (ESP) was investigated. The results showed that the compression ratios of magnetic field, density, and temperature varied within certain ranges, and the shock speed and shock obliquity also showed variability. The spectral indices of ESP both upstream and downstream of the shock exhibited similarities, suggesting local acceleration at the shock. Additionally, the study found that the derived shock properties were representative within specific time windows, beyond which they no longer held true.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Zheyi Ding, Gang Li, Adolfo Santa Fe Duenas, Robert W. Ebert, Nicolas Wijsen, Stefaan Poedts
Summary: We examined the East-West asymmetry of the peak intensity in energetic storm particle (ESP) events using a model. We found that the peak intensity is higher at the eastern flank and positively correlates with injection efficiency. The asymmetry for heavy ions depends on ion energy and shows reasonable agreement with measurements.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
